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Sample records for rainfed lowland rice

  1. The effects of water regime on phosphorus responses of rainfed lowland rice cultivars.

    PubMed

    Huguenin-Elie, O; Kirk, G J D; Frossard, E

    2009-01-01

    Soil phosphorus (P) solubility declines sharply when a flooded soil drains, and an important component of rice (Oryza sativa) adaptation to rainfed lowland environments is the ability to absorb and utilize P under such conditions. The aim of this study was to test the hypothesis that rice cultivars differ in their P responses between water regimes because P uptake mechanisms differ. Six lowland rice cultivars (three considered tolerant of low P soils, three sensitive) were grown in a factorial experiment with three water regimes (flooded, moist and flooded-then-moist) and four soil P levels, and growth and P uptake were measured. Small volumes of soil were used to maximize inter-root competition and uptake per unit root surface. The results were compared with the predictions of a model allowing for the effects of water regime on P solubility and diffusion. The plants were P stressed but not water stressed in all the water regimes at all P levels except the higher P additions in the flooded soil. The cultivar rankings scarcely differed between the water regimes and P additions. In all the treatments, the soil P concentrations required to explain the measured uptake were several times the concentration of freely available P in the soil. The cultivar rankings were driven more by differences in growth habit than specific P uptake mechanisms, so the hypothesis cannot be corroborated with these data. Evidently all the plants could tap sparingly soluble forms of P by releasing a solubilizing agent or producing a greater root length than measured, or both. However, any cultivar differences in this were not apparent in greater net P uptake, possibly because the restricted rooting volume meant that additional P uptake could not be converted into new root growth to explore new soil volumes.

  2. Weed communities of rain-fed lowland rice vary with infestation by Rhamphicarpa fistulosa

    NASA Astrophysics Data System (ADS)

    Houngbédji, Tossimidé; Dessaint, Fabrice; Nicolardot, Bernard; Shykoff, Jacqui A.; Gibot-Leclerc, Stéphanie

    2016-11-01

    The facultative hemiparasitic plant Rhamphicarpa fistulosa (Orobanchaceae) thrives in seasonally wet soils in sub-Saharan Africa, mainly in marginal lowland rice growing environments where weeds are already a major constraint for rice production. Because lowland rice production is increasing in tropical Africa, it is important to ascertain the influence of R. fistulosa on weed plant communities in these rice-growing habitats. We investigated weed plant community richness and composition at four different levels of R. fistulosa infestation across two years of surveys from lowland rice fields in northern Togo (West Africa). Despite a lack of significant differences in community richness among sites with different R. fistulosa infestation levels, there were significant differences in community composition, both when estimated from presence-absence data and from relative abundance data, after controlling statistically for geographic proximity among sites. Rhamphicarpa fistulosa infestation, therefore, may influence the competitive balance between rice and its weeds and shape weed community structure. However, experimental studies are required to elucidate the weed host range of R. fistulosa and the direct and indirect effects of this hemiparasite in rice fields in order to predict its net impact on rice and its weed species.

  3. Comparison of Sub1 markers and their combinations for submergence tolerance and analysis of adaptation strategies of rice in rainfed lowland ecology.

    PubMed

    Pradhan, Sharat Kumar; Barik, Saumya Ranjan; Sahoo, Jayashree; Pandit, Elssa; Nayak, Deepak Kumar; Pani, Dipti Ranjan; Anandan, Annamalai

    2015-10-01

    Ninety lowland rice cultivars of the eastern region of India were collected and screened for submergence and water logging tolerance and further used for validating the efficiency of molecular markers and their combinations for submergence tolerance. Submergence tolerance and elongation ability of the tested genotypes were measured in screening tanks along with tolerant and susceptible checks. The genotypes FR13A, Khoda, CR Dhan 300, Savitri Sub1, IR64 Sub1, IC-568009 and IC-568842 exhibited high submergence tolerance may be used as donor in the breeding program. Landrace 'Khoda' showed tolerance to submergence with moderate elongation ability for adaption. Boitalpakhia, Gayatri, Atiranga, Aghonibora, Chakaakhi, Moti, IC-567993 and IC-568921 possessed both characters of moderate elongation ability and moderate tolerance to submergence. Both of these traits are required for lowland varieties of eastern India to survive under flash flood and accumulated stagnant water conditions. RM8300, Sub1A203, AEX, Sub1BC2 and Sub1C173 were employed for molecular screening to identify the submergence-tolerant genotypes. Sub1A203 was capable of differentiating the tolerant and susceptible genotypes into groups. RM8300 and Sub1BC2 could also differentiate the genotypes with inclusion of some susceptible genotypes. The AEX and Sub1C173 marker could not show discrimination among the genotypes with respect to the traits. Using Sub1A203+Sub1BC2 was better amongst the combinations studied. The results of the study indicated a trend toward a negative association of Sub1BC2 with submergence tolerance while AEX and Sub1C marker did not show any significant association. The donors identified can be useful as parental lines while the molecular markers can be used for marker-assisted breeding work. Copyright © 2015 Académie des sciences. Published by Elsevier SAS. All rights reserved.

  4. Tracing the allocation of water in rainfed rice ecosystem by partitioning evapotranspiration of rainfed rice (Oryza Sativa L.)

    NASA Astrophysics Data System (ADS)

    Nay-Htoon, Bhone; Dubbert, Maren; Wei, Xue; Cuntz, Matthias; Ko, Jonghan; Tenhunen, John; Werner, Christiane

    2015-04-01

    To understand productive and unproductive water use of crop production, partitioning evapotranspiration (ET ) into evaporation (E) and transpiration (T ) is important. Water movements within the eco-hydrologic cycle of agroecosystems can be traced by stable oxygen isotopes of water (δ18O) and plant transpiration and soil evaporation can also be estimated by tracing the δ18O. We quantified the contribution of transpiration to total ecosystem evapotranspiration of rainfed rice field by a stable oxygen isotope approach and FAO 56 dual crop modelling approach. Our study aims to provide quantification of ecosystem water cycle of rainfed rice by partitioning productive and unproductive water use since productivity and water use of rice which is a highly water demanding agroecosystem, is under intense research. Crop season total evapotranspiration fluxes from rainfed rice was mainly dominated by transpiration (T to ET contribution (T /ET ) = 65%) and domination of transpiration over evaporation fluxes was noted since early vegetative stage (Leaf Area Index = 0.8 m2 m-2) until harvesting. T /ET of rainfed rice fluctuated with changes in soil water content (SWC) and the highest T /ET was found at SWC of 0.34 m3 m-3, during seedling stage. Our results demonstrate that partitioning ET by FAO 56 dual crop model is in a good agreement with δ18O isotope based ET partitioning results. Using monthly mean values of leaf resistance and vegetation index derived crop coefficients instead of original fixed parameters of the FAO 56 dual crop model resulted better agreement with δ18O isotope based ET partitioning.

  5. Mapping regional risks from climate change for rainfed rice cultivation in India.

    PubMed

    Singh, Kuntal; McClean, Colin J; Büker, Patrick; Hartley, Sue E; Hill, Jane K

    2017-09-01

    Global warming is predicted to increase in the future, with detrimental consequences for rainfed crops that are dependent on natural rainfall (i.e. non-irrigated). Given that many crops grown under rainfed conditions support the livelihoods of low-income farmers, it is important to highlight the vulnerability of rainfed areas to climate change in order to anticipate potential risks to food security. In this paper, we focus on India, where ~ 50% of rice is grown under rainfed conditions, and we employ statistical models (climate envelope models (CEMs) and boosted regression trees (BRTs)) to map changes in climate suitability for rainfed rice cultivation at a regional level (~ 18 × 18 km cell resolution) under projected future (2050) climate change (IPCC RCPs 2.6 and 8.5, using three GCMs: BCC-CSM1.1, MIROC-ESM-CHEM, and HadGEM2-ES). We quantify the occurrence of rice (whether or not rainfed rice is commonly grown, using CEMs) and rice extent (area under cultivation, using BRTs) during the summer monsoon in relation to four climate variables that affect rice growth and yield namely ratio of precipitation to evapotranspiration (PER), maximum and minimum temperatures (Tmax and Tmin ), and total rainfall during harvesting. Our models described the occurrence and extent of rice very well (CEMs for occurrence, ensemble AUC = 0.92; BRTs for extent, Pearson's r = 0.87). PER was the most important predictor of rainfed rice occurrence, and it was positively related to rainfed rice area, but all four climate variables were important for determining the extent of rice cultivation. Our models project that 15%-40% of current rainfed rice growing areas will be at risk (i.e. decline in climate suitability or become completely unsuitable). However, our models project considerable variation across India in the impact of future climate change: eastern and northern India are the locations most at risk, but parts of central and western India may benefit from increased

  6. Effects of beneficial microorganisms on lowland rice development.

    PubMed

    Nascente, Adriano Stephan; de Filippi, Marta Cristina Corsi; Lanna, Anna Cristina; de Sousa, Thatyane Pereira; de Souza, Alan Carlos Alves; da Silva Lobo, Valácia Lemes; da Silva, Gisele Barata

    2017-09-19

    Microorganisms can promote plant growth by increasing phytomass production, nutrient uptake, photosynthesis rates, and grain yield, which can result in higher profits for farmers. However, there is limited information available about the physiological characteristics of lowland rice after treatment with beneficial microorganisms in the tropical region. This study aimed to determine the effects of different beneficial microorganisms and various application forms on phytomass production, gas exchange, and nutrient contents in the lowland rice cultivar 'BRS Catiana' in a tropical region. The experiment was performed under greenhouse conditions utilizing a completely randomized design and a 7 × 3 + 1 factorial scheme with four replications. The treatments consisted of seven microorganisms, including the rhizobacterial isolates BRM 32113, BRM 32111, BRM 32114, BRM 32112, BRM 32109, and BRM 32110 and Trichoderma asperellum pooled isolates UFRA-06, UFRA-09, UFRA-12, and UFRA-52, which were applied using three different methods (microbiolized seed, microbiolized seed + soil drenched with a microorganism suspension at 7 and 15 days after sowing (DAS), and microbiolized seed + plant spraying with a microorganism suspension at 7 and 15 DAS) with a control (water). The use of microorganisms can provide numerous benefits for rice in terms of crop growth and development. The microorganism types and methods of application positively and differentially affected the physiological characteristics evaluated in the experimental lowland rice plants. Notably, the plants treated with the bioagent BRM 32109 on the seeds and on seeds + soil produced plants with the highest dry matter biomass, gas exchange rate, and N, P, Fe, and Mg uptake. Therefore, our findings indicate strong potential for the use of microorganisms in lowland rice cultivation systems in tropical regions. Currently, an additional field experiment is in its second year to validate the beneficial result reported

  7. Mosquito (Diptera: Culicidae) and predator abundance in irrigated and rain-fed rice fields in north Sulawesi, Indonesia.

    PubMed

    Mogi, M; Memah, V; Miyagi, I; Toma, T; Sembel, D T

    1995-05-01

    Immature mosquito species composition and abundance were studied in irrigated and rain-fed rice fields of North Sulawesi, Indonesia. Irrigated rice fields were characterized by the prevalence of aquatic macrophytes and cyprinodont larvivorous fish, Aplocheilus panchax (Hamilton), but abundance per dip of most aquatic insect predators was lower than that in rain-fed rice fields. Anopheles peditaeniatus (Leicester), Culex vishnui Theobald, and Culex tritaeniorhynchus Giles, were dominant in both irrigated and rain-fed fields, but the abundance of the Culex species was lower in irrigated fields. The effect of irrigation system introduction on regional mosquito abundance cannot be evaluated by the enlarged surface water area alone. Changes in habitat quality, expressed as the abundance per dip (index of density per unit water area), also need to be considered.

  8. Multinuclear magnetic resonance analysis of two humic acid fractions from lowland rice soils.

    PubMed

    Mahieu, N; Olk, D C; Randall, E W

    2002-01-01

    To determine the effects of intensive cropping of tropical lowland rice (Oryza sativa L.) and the associated long-term soil submergence on chemical properties of soil organic matter, we used solid-state 13C and 15N and solution 31P nuclear magnetic resonance (NMR) spectroscopy to analyze the labile mobile humic acid (MHA) and the more recalcitrant calcium humate (CaHA) fractions extracted from a series of soils supporting several long-term field experiments in the Philippines. The soils varied mainly in degree of submergence and cropping intensity, ranging from a rainfed rice field without soil submergence to irrigated double- and triple-cropped fields in which soil remains submerged almost all year long. As reported previously, all analyses associated increasing intensity of rice cropping with larger proportions of less humified material in the MHA and CaHA, such as diester phosphorus (P), amide nitrogen (N), and phenolic carbon (C). We established significant correlations between proportions of various spectral areas as well as between some spectral areas and other humic acid (HA) properties such as visible light absorption and free radical concentration (positive indices of humification) and hydrogen (H) concentration (negative index of humification). For example, spectral proportions of heterocyclic N were positively, and proportions of amide N and phenolic C negatively, correlated with visible light absorption and free radical concentration, and each of these spectral proportions had an opposite sign when correlated with H concentration. The correlations of N-alkyl C proportions were the strongest with these properties and with other functional group proportions.

  9. Traits and QTLs for development of dry direct-seeded rainfed rice varieties

    PubMed Central

    Sandhu, Nitika; Torres, Rolando O.; Sta Cruz, Ma. Teresa; Maturan, Paul Cornelio; Jain, Rajinder; Kumar, Arvind; Henry, Amelia

    2015-01-01

    The development of rice varieties for dry direct-seeded conditions can be accelerated by selecting suitable traits. In the present investigation, traits hypothesized to be important for direct-seeded conditions in rainfed systems, including seedling emergence, early vegetative vigour, nutrient uptake, nodal root number, and root hair length and density, were characterized to study the genetic control of these traits and their relationship with grain yield under seedling- and reproductive-stage drought stress. Two BC2F4 mapping populations derived from crosses of Aus276, a drought-tolerant aus variety, with MTU1010 and IR64, high-yielding indica mega-varieties, were developed and studied to identify quantitative trait loci (QTLs) that showed large and consistent effects. A total of 26 QTLs associated with 23 traits and 20 QTLs associated with 13 traits were mapped in the Aus276/3*IR64 and Aus276/3*MTU1010 populations, respectively. qGY6.1, qGY10.1, qGY1.1, and qEVV9.1 were found to be effective in both populations under a wide range of conditions. QTLs for several seedling-stage traits co-located with QTLs for grain yield, including early vegetative vigour and root hair length. On chromosome 5, several QTLs for nutrient uptake co-located with QTLs for root hair density and nematode gall rating. Six lines were selected from both populations based on grain yield and the presence of QTLs, and these lines typically showed improved seedling-stage traits (nodal root number, dry shoot weight, and root hair length and density). The co-located QTLs identified here can be used in research aimed at increasing the yield and adaptability of rainfed rice to direct-seeded conditions. PMID:25336682

  10. Human energy expenditure in lowland rice cultivation in Malaysia.

    PubMed

    Nawi, N M; Yahya, A; Chen, G; Bockari-Gevao, S M; Maraseni, T N

    2012-01-01

    A study was undertaken to evaluate the human energy consumption of various field operations involved in lowland rice cultivation in Malaysia. Based on recorded average heart rates, fertilizing was found to be the most strenuous operation, with an average heart rate of 138 beats min(-1). There were no significant differences in the average heart rates of the subjects among the individual tasks within the first plowing, second plowing, and harvesting operations, with the average heart rates for these three tasks being 116, 106, and 106 beats min(-1), respectively. The corresponding energy expenditures were 3.90, 3.43, and 3.35 kcal min(-1). Loading the seed into the blower tank and broadcasting the seed were the most critical tasks for the seed broadcasting operation, with average heart rates of 124 and 136 beats min(-1), respectively. The highest energy expenditure of 418.38 kcal ha(-1) was observed for seed broadcasting, and the lowest energy expenditure of 127.96 kcal ha(-1) was for second plowing. The total seasonal human energy expenditure for rice cultivation was estimated to be 5810.71 kcal ha(-1), 55.7% of which was spent on pesticide spraying. Although the sample size in this study was relatively small, the results indicated that human energy expenditure per unit area (kcal ha(-1)) was positively linked to the average heart rate of the subjects and negatively linked to the field capacity. Thus, mechanization of certain tasks could decrease worker physical effort and fatigue and increase production.

  11. Crop and varietal diversification of rainfed rice based cropping systems for higher productivity and profitability in Eastern India

    PubMed Central

    Panda, B. B.; Raja, R.; Singh, Teekam; Tripathi, R.; Shahid, M.; Nayak, A. K.

    2017-01-01

    Rice-rice system and rice fallows are no longer productive in Southeast Asia. Crop and varietal diversification of the rice based cropping systems may improve the productivity and profitability of the systems. Diversification is also a viable option to mitigate the risk of climate change. In Eastern India, farmers cultivate rice during rainy season (June–September) and land leftovers fallow after rice harvest in the post-rainy season (November–May) due to lack of sufficient rainfall or irrigation amenities. However, in lowland areas, sufficient residual soil moistures are available in rice fallow in the post-rainy season (November–March), which can be utilized for raising second crops in the region. Implementation of suitable crop/varietal diversification is thus very much vital to achieve this objective. To assess the yield performance of rice varieties under timely and late sown conditions and to evaluate the performance of dry season crops following them, three different duration rice cultivars were transplanted in July and August. In dry season several non-rice crops were sown in rice fallow to constitute a cropping system. The results revealed that tiller occurrence, biomass accumulation, dry matter remobilization, crop growth rate, and ultimately yield were significantly decreased under late transplanting. On an average, around 30% yield reduction obtained under late sowing may be due to low temperature stress and high rainfall at reproductive stages of the crop. Dry season crops following short duration rice cultivars performed better in terms of grain yield. In the dry season, toria was profitable when sown earlier and if sowing was delayed greengram was suitable. Highest system productivity and profitability under timely sown rice may be due to higher dry matter remobilization from source to sink. A significant correlation was observed between biomass production and grain yield. We infer that late transplanting decrease the tiller occurrence and

  12. Crop and varietal diversification of rainfed rice based cropping systems for higher productivity and profitability in Eastern India.

    PubMed

    Lal, B; Gautam, Priyanka; Panda, B B; Raja, R; Singh, Teekam; Tripathi, R; Shahid, M; Nayak, A K

    2017-01-01

    Rice-rice system and rice fallows are no longer productive in Southeast Asia. Crop and varietal diversification of the rice based cropping systems may improve the productivity and profitability of the systems. Diversification is also a viable option to mitigate the risk of climate change. In Eastern India, farmers cultivate rice during rainy season (June-September) and land leftovers fallow after rice harvest in the post-rainy season (November-May) due to lack of sufficient rainfall or irrigation amenities. However, in lowland areas, sufficient residual soil moistures are available in rice fallow in the post-rainy season (November-March), which can be utilized for raising second crops in the region. Implementation of suitable crop/varietal diversification is thus very much vital to achieve this objective. To assess the yield performance of rice varieties under timely and late sown conditions and to evaluate the performance of dry season crops following them, three different duration rice cultivars were transplanted in July and August. In dry season several non-rice crops were sown in rice fallow to constitute a cropping system. The results revealed that tiller occurrence, biomass accumulation, dry matter remobilization, crop growth rate, and ultimately yield were significantly decreased under late transplanting. On an average, around 30% yield reduction obtained under late sowing may be due to low temperature stress and high rainfall at reproductive stages of the crop. Dry season crops following short duration rice cultivars performed better in terms of grain yield. In the dry season, toria was profitable when sown earlier and if sowing was delayed greengram was suitable. Highest system productivity and profitability under timely sown rice may be due to higher dry matter remobilization from source to sink. A significant correlation was observed between biomass production and grain yield. We infer that late transplanting decrease the tiller occurrence and assimilate

  13. Genetic Differentiation Revealed by Selective Loci of Drought-Responding EST-SSRs between Upland and Lowland Rice in China

    PubMed Central

    Xia, Hui; Zheng, Xiaoguo; Chen, Liang; Gao, Huan; Yang, Hua; Long, Ping; Rong, Jun; Lu, Baorong; Li, Jiajia; Luo, Lijun

    2014-01-01

    Upland and lowland rice (Oryza sativa L.) represent two of the most important rice ecotypes adapted to ago-ecosystems with contrasting soil-water conditions. Upland rice, domesticated in the water-limited environment, contains valuable drought-resistant characters that can be used in water-saving breeding. Knowledge about the divergence between upland and lowland rice will provide valuable cues for the evolution of drought-resistance in rice. Genetic differentiation between upland and lowland rice was explored by 47 Simple Sequence Repeats (SSRs) located in drought responding expressed sequence tags (ESTs) among 377 rice landraces. The morphological traits of drought-resistance were evaluated in the field experiments. Different outlier loci were detected in the japonica and indica subspecies, respectively. Considerable genetic differentiation between upland and lowland rice on these outlier loci was estimated in japonica (Fst = 0.258) and indica (Fst = 0.127). Furthermore, populations of the upland and lowland ecotypes were clustered separately on these outlier loci. A significant correlation between genetic distance matrices and the dissimilarity matrices of drought-resistant traits was determined, indicating a certain relationship between the upland-lowland rice differentiation and the drought-resistance. Divergent selections occur between upland and lowland rice on the drought-resistance as the Qsts of some drought-resistant traits are significantly higher than the neutral Fst. In addition, the upland- and lowland-preferable alleles responded differently among ecotypes or allelic types under osmotic stress. This shows the evolutionary signature of drought resistance at the gene expression level. The findings of this study can strengthen our understanding of the evolution of drought-resistance in rice with significant implications in the improvement of rice drought-resistance. PMID:25286109

  14. Genetic differentiation revealed by selective loci of drought-responding EST-SSRs between upland and lowland rice in China.

    PubMed

    Xia, Hui; Zheng, Xiaoguo; Chen, Liang; Gao, Huan; Yang, Hua; Long, Ping; Rong, Jun; Lu, Baorong; Li, Jiajia; Luo, Lijun

    2014-01-01

    Upland and lowland rice (Oryza sativa L.) represent two of the most important rice ecotypes adapted to ago-ecosystems with contrasting soil-water conditions. Upland rice, domesticated in the water-limited environment, contains valuable drought-resistant characters that can be used in water-saving breeding. Knowledge about the divergence between upland and lowland rice will provide valuable cues for the evolution of drought-resistance in rice. Genetic differentiation between upland and lowland rice was explored by 47 Simple Sequence Repeats (SSRs) located in drought responding expressed sequence tags (ESTs) among 377 rice landraces. The morphological traits of drought-resistance were evaluated in the field experiments. Different outlier loci were detected in the japonica and indica subspecies, respectively. Considerable genetic differentiation between upland and lowland rice on these outlier loci was estimated in japonica (Fst = 0.258) and indica (Fst = 0.127). Furthermore, populations of the upland and lowland ecotypes were clustered separately on these outlier loci. A significant correlation between genetic distance matrices and the dissimilarity matrices of drought-resistant traits was determined, indicating a certain relationship between the upland-lowland rice differentiation and the drought-resistance. Divergent selections occur between upland and lowland rice on the drought-resistance as the Qsts of some drought-resistant traits are significantly higher than the neutral Fst. In addition, the upland- and lowland-preferable alleles responded differently among ecotypes or allelic types under osmotic stress. This shows the evolutionary signature of drought resistance at the gene expression level. The findings of this study can strengthen our understanding of the evolution of drought-resistance in rice with significant implications in the improvement of rice drought-resistance.

  15. Phosphorus and Iron Deficiencies Influences Rice Shoot Growth in an Oxygen Dependent Manner: Insight from Upland and Lowland Rice

    PubMed Central

    Mongon, Jenjira; Chaiwong, Nanthana; Bouain, Nadia; Prom-u-thai, Chanakan; Secco, David; Rouached, Hatem

    2017-01-01

    Rice is the main staple crop for one-third of the world population. To maximize yields, large quantities and constant input of fertilizers containing essential nutrients such as phosphorus (P) and iron (Fe) are added. Rice can germinate in both aerobic and anaerobic conditions, but the crosstalk between oxygen (O2) and nutrients such as P and Fe on plant growth remains obscure. The aim of this work was to test whether such interactions exist, and, if so, if they are conserved between up- and lowland rice varieties. To do so, we assessed shoot and root biomass as well as inorganic phosphate (Pi) accumulation in four rice varieties, including two lowland rice varieties Nipponbare and Suphanburi 1 (SPR1) (adapted to non-aerated condition) and two upland rice varieties CMU122 and Sew Mae Jun (SMJ) (adapted to aerated condition) under various conditions of Pi and/or Fe deficiencies, in aerated and non-areated solution. Under these different experimental conditions, our results revealed that the altered shoot biomass in Nipponbare and SPR1 was O2-dependent but to a lesser extent in CMU122 and SMJ cultivars. In this perspective, discovering the biological significance and molecular basis of these mineral elements and O2 signal interaction is needed to fully appreciate the performance of plants to multiple environmental changes. PMID:28287426

  16. Phosphorus and Iron Deficiencies Influences Rice Shoot Growth in an Oxygen Dependent Manner: Insight from Upland and Lowland Rice.

    PubMed

    Mongon, Jenjira; Chaiwong, Nanthana; Bouain, Nadia; Prom-U-Thai, Chanakan; Secco, David; Rouached, Hatem

    2017-03-10

    Rice is the main staple crop for one-third of the world population. To maximize yields, large quantities and constant input of fertilizers containing essential nutrients such as phosphorus (P) and iron (Fe) are added. Rice can germinate in both aerobic and anaerobic conditions, but the crosstalk between oxygen (O₂) and nutrients such as P and Fe on plant growth remains obscure. The aim of this work was to test whether such interactions exist, and, if so, if they are conserved between up- and lowland rice varieties. To do so, we assessed shoot and root biomass as well as inorganic phosphate (Pi) accumulation in four rice varieties, including two lowland rice varieties Nipponbare and Suphanburi 1 (SPR1) (adapted to non-aerated condition) and two upland rice varieties CMU122 and Sew Mae Jun (SMJ) (adapted to aerated condition) under various conditions of Pi and/or Fe deficiencies, in aerated and non-areated solution. Under these different experimental conditions, our results revealed that the altered shoot biomass in Nipponbare and SPR1 was O₂-dependent but to a lesser extent in CMU122 and SMJ cultivars. In this perspective, discovering the biological significance and molecular basis of these mineral elements and O₂ signal interaction is needed to fully appreciate the performance of plants to multiple environmental changes.

  17. A Comparative Molecular-Physiological Study of Submergence Response in Lowland and Deepwater Rice1

    PubMed Central

    Van Der Straeten, Dominique; Zhou, Zhongyi; Prinsen, Els; Van Onckelen, Harry A.; Van Montagu, Marc C.

    2001-01-01

    Survival of rice (Oryza sativa) upon an extreme rise of the water level depends on rapid stem elongation, which is mediated by ethylene. A genomic clone (OS-ACS5) encoding 1-aminocyclopropane-1-carboxylic acid (ACC) synthase, which catalyzes a regulatory step in ethylene biosynthesis, has been isolated from cv IR36, a lowland rice variety. Expression was induced upon short- and long-term submergence in cv IR36 and in cv Plai Ngam, a Thai deepwater rice variety. Under hypoxic conditions, abscisic acid and gibberellin had a reciprocal opposite effect on the activity of OS-ACS5. Gibberellin up-regulated and abscisic acid down-regulated OS-ACS5 mRNA accumulation. Growth experiments indicated that lowland rice responded to submergence with a burst of growth early on, but lacked the ability to sustain elongation growth. Sustained growth, characteristic for deepwater rice, was correlated with a prolonged induction of OS-ACS5. In addition, a more pronounced capacity to convert ACC to ethylene, a limited ACC conjugation, and a high level of endogenous gibberellin20 were characteristic for the deepwater variety. An elevated level of OS-ACS5 messenger was found in cv IR36 plants treated with exogenous ACC. This observation was concomitant with an increase in the capacity of converting ACC to ethylene and in elongation growth, and resulted in prolonged survival. In conclusion, OS-ACS5 is involved in the rapid elongation growth of deepwater rice by contributing to the initial and long-term increase in ethylene levels. Our data also suggest that ACC limits survival of submerged lowland rice seedlings. PMID:11161052

  18. A comparative molecular-physiological study of submergence response in lowland and deepwater rice.

    PubMed

    Van Der Straeten, D; Zhou, Z; Prinsen, E; Van Onckelen, H A; Van Montagu, M C

    2001-02-01

    Survival of rice (Oryza sativa) upon an extreme rise of the water level depends on rapid stem elongation, which is mediated by ethylene. A genomic clone (OS-ACS5) encoding 1-aminocyclopropane-1-carboxylic acid (ACC) synthase, which catalyzes a regulatory step in ethylene biosynthesis, has been isolated from cv IR36, a lowland rice variety. Expression was induced upon short- and long-term submergence in cv IR36 and in cv Plai Ngam, a Thai deepwater rice variety. Under hypoxic conditions, abscisic acid and gibberellin had a reciprocal opposite effect on the activity of OS-ACS5. Gibberellin up-regulated and abscisic acid down-regulated OS-ACS5 mRNA accumulation. Growth experiments indicated that lowland rice responded to submergence with a burst of growth early on, but lacked the ability to sustain elongation growth. Sustained growth, characteristic for deepwater rice, was correlated with a prolonged induction of OS-ACS5. In addition, a more pronounced capacity to convert ACC to ethylene, a limited ACC conjugation, and a high level of endogenous gibberellin(20) were characteristic for the deepwater variety. An elevated level of OS-ACS5 messenger was found in cv IR36 plants treated with exogenous ACC. This observation was concomitant with an increase in the capacity of converting ACC to ethylene and in elongation growth, and resulted in prolonged survival. In conclusion, OS-ACS5 is involved in the rapid elongation growth of deepwater rice by contributing to the initial and long-term increase in ethylene levels. Our data also suggest that ACC limits survival of submerged lowland rice seedlings.

  19. Municipal waste compost as an alternative to cattle manure for supplying potassium to lowland rice.

    PubMed

    Bhattacharyya, P; Chakrabarti, K; Chakraborty, A; Nayak, D C; Tripathy, S; Powell, M A

    2007-01-01

    The importance of the use of potassium in agriculture is increasing in South Asia for making most productive use of the nutrient in terms of economic returns. Nutrient supply traditionally by cattle manure is constrained by its insufficient availability. Municipal waste compost may be an alternative source of nutrient supplements. Field experiments were conducted at the Experimental Farm of Calcutta University, West Bengal, India during the wet seasons of 1997, 1998 and 1999 on flooded lowland rice. Potassium fractions in municipal waste compost and cattle manure were determined by sequential extraction and also the potassium uptake by rice to compare the effectiveness of municipal waste compost with traditional manure. Potassium was significantly bound to the organic matter in municipal waste compost. Potassium uptake by rice grain and straw increased significantly with the combined application of organics and fertilizers and it was higher in grain than in straw. Water-soluble and non-exchangeable potassium contents of municipal waste compost and cattle manure were highly correlated with the uptake of potassium by straw and grain. Exchangeable and residual potassium were also significantly correlated with the uptake of potassium by straw and grain of rice. Much higher uptake of K in rice straw and rain resulted from applying the manures in conjunction with fertilizers than when applied singly.

  20. Suitability Evaluation for Lowland Rice in Inland Valleys in West Africa

    NASA Astrophysics Data System (ADS)

    Hideto, Fujii; Muralikrishna, Gumma; Prasad, Thenkabail; Regassa, Namara

    A GIS based model developed by the authors are applied for selecting suitable rice cultivation area in inland valleys that has high potential for rice production in West Africa where rice consumption is increasing very rapidly. The model has the following features. 1) The model is to evaluate the suitability of the land for lowland rice based on score distribution maps respectively made by the data of 29 evaluation parameters. 2) The parameters are classified into 4 categories; bio-physical, technical, socio-economic and health-environmental parameters. 3) Each scored map (layer) is integrated to obtain total scores by multiplying a weight which is determined by the importance of parameters. The suitability for rice in two study sites was evaluated using the model. Mankran and Jolo-Kwaha watershed selected as the study sites from different agro-ecological zone in Ghana. Applying the data of 12 parameters acquired in the study sites to the model, “very suitable” or “suitable” occupies around 30% in Mankran study site and around 60% in Jolo-Kwaha study site.

  1. Incorporation of Bacterial Blight Resistance Genes Into Lowland Rice Cultivar Through Marker-Assisted Backcross Breeding.

    PubMed

    Pradhan, Sharat Kumar; Nayak, Deepak Kumar; Pandit, Elssa; Behera, Lambodar; Anandan, Annamalai; Mukherjee, Arup Kumar; Lenka, Srikanta; Barik, Durga Prasad

    2016-07-01

    Bacterial blight (BB) of rice caused by Xanthomonas oryzae pv. oryzae is a major disease of rice in many rice growing countries. Pyramided lines carrying two BB resistance gene combinations (Xa21+xa13 and Xa21+xa5) were developed in a lowland cultivar Jalmagna background through backcross breeding by integrating molecular markers. In each backcross generation, markers closely linked to the disease resistance genes were used to select plants possessing the target genes. Background selection was continued in those plants carrying resistant genes until BC(3) generation. Plants having the maximum contribution from the recurrent parent genome were selected in each generation and hybridized with the recipient parent. The BB-pyramided line having the maximum recipient parent genome recovery of 95% was selected among BC3F1 plants and selfed to isolate homozygous BC(3)F(2) plants with different combinations of BB resistance genes. Twenty pyramided lines with two resistance gene combinations exhibited high levels of tolerance against the BB pathogen. In order to confirm the resistance, the pyramided lines were inoculated with different X. oryzae pv. oryzae strains of Odisha for bioassay. The genotypes with combination of two BB resistance genes conferred high levels of resistance to the predominant X. oryzae pv. oryzae isolates prevalent in the region. The pyramided lines showed similarity with the recipient parent with respect to major agro-morphologic traits.

  2. Characterization of rice (Oryza sativa L.) genotypes on the basis of morpho-physiological and biochemical traits grown under aerobic situation in rainfed ecosystem .

    PubMed

    Kumar, Santosh; Dwivedi, Sharad Kumar; Singh, S S; Kumar, Sanjeev; Sundaram, R K; Shivani; Mall, A K

    2015-07-01

    The objective of the present study was to examine the effect of aerobic situation on yield, physiological and biochemical traits of advanced breeding lines of rice. Experiment was conducted with two set of rice genotypes under two water regimes (aerobic and irrigated), during three consecutive wet seasons 2010-2012. Significant decrease in yield was observed in rice genotypes grown under aerobic situation as compared to the irrigated ones. Promising rice genotypes having the ability to maintain high plant biomass, harvest index, early vegetative vigour, improved physiological and biochemical traits in terms of relative water content (RWC), leaf area index (LAI), total soluble sugar, starch, protien and proline content help to sustain higher grain yield under aerobic situation. The yield gap between aerobic and irrigated rice ranged between 24% to 68%. Grain yield showed positive correlation with harvest index (0.434), test weight (0.647), plant biomass (0.411) and effective tiller numbers (0.473), whereas spikelet sterility was negative associated (-0.380). The current study suggested that promising genotypes viz., IR77298-14-1-2-130-2, IR84899-B-182-3-1-1-2, IR84887-B-157-38-1-1-3 and IR 84899-B-179-1-1-1-2 for aerobic situation, showing yield advantage due to better performance of physiological and biochemical traits, might be adopted in large area of rainfed ecosystem as well as in irrigated areas where water scarcity was a major problem.

  3. Optimizing tillage schedule for maintaining activity of the arbuscular mycorrhizal fungal population in a rainfed upland rice (Oryza sativa L.) agro-ecosystem.

    PubMed

    Maiti, D; Variar, M; Singh, R K

    2011-04-01

    Rainfed uplands in India are predominantly mono-cropped with rice (Oryza sativa L.) in the wet season (June/July to September/October) and grown under aerobic soil conditions. The remaining fallow period (winter followed by summer) of about 8-9 months leads to natural crash in the population of native arbuscular mycorrhizal fungi (AMF) in the soil. Attempts have been made to minimize this population crash by reducing soil disturbance-induced deleterious effects on native AMF activity of improperly scheduled off-season tillage, an agronomic recommendation for weed and disease (soil-borne) management, practiced by the upland farmers. On-farm (farmers' field) evaluation of effects of all suitable off-season tillage schedule combinations on rice during wet seasons of 2004, 2005, and 2006 revealed that a maximum of two off-season tillage schedules with a minimum gap of 13 weeks between them minimized the population crash of native AMF with a concomitant increase in phosphorus (P) uptake and grain yield of upland rice (variety "Vandana").

  4. Cluster analysis of lowland and upland rice cultivars based on grain quality attributes

    USDA-ARS?s Scientific Manuscript database

    Rice is cropped in many countries all over the world and plays an important role in human nutrition as well as in agricultural economics, besides its social importance. Embrapa Rice and Beans is responsible for national rice enhancement programs and is conducting breeding projects to increase yield ...

  5. Economy of fertilizer nitrogen through organic sources in rain-fed rice-legume cropping systems in West Bengal, India.

    PubMed

    Puste, A M; Bandyopadhyay, S; Das, D K

    2001-12-11

    Field experiments were conducted at a farmers" plot adjacent to the Regional Research Station, red and laterite zone, Sub-center Sekhampur (Birbhum district) of West Bengal, India, situated 23 degrees 24' N latitude, 87 degrees 24' E longitude, to study the effect of different bio- and organic sources of nutrients instead of total fertilizer N in terms of crop productivity in the sequence and building up of soil fertility. During the wet seasons of 1997 and 1998, 12 combinations of bio- and organic sources (crop residues, well decomposed cow dung, dhanicha as green manure) were substituted for 25-50% of N fertilizer applied on transplanted rice (Cv. IR 36). Subsequently, during the winters of 1997-1998 and 1998-1999, leguminous pulse crops like lentil (Lens culinaris [L.] Medic.), gram ( Cicer arietinum L.) and lathyrus (Lathyrus sativus L.) were grown with and without inoculation of Rhizobium. Results revealed that the application of inorganic N in combination with organic sources exhibited a significant increase in rice yield (3.60-3.84 t ha(-1) ) compared to the yield from sole application of N (3.19-3.26 t ha(-1) ). The study showed that about 25% of total applied N was saved without significant yield reduction with simultaneous improvement of soil physical properties (pH, organic matter, available N, P, K, and CEC). Seed yield of pulses (lentil, gram, and lathyrus) were more pronounced in the treatment inoculated with Rhizobium, with a saving of 42.6-48.4 kg N ha(-1). Therefore, the results suggest that the combined application of inorganic and organic N sources in a 75:25 ratio is a superior N-management practice with regards to crop yields as well as improvement of soil fertility.

  6. Seasonal assessment of greenhouse gas emission from irrigated lowland rice field under infrared warming

    USDA-ARS?s Scientific Manuscript database

    Rice fields are considered as one of the major sources of methane (CH4), and they also emit nitrous oxide (N2O). A field experiment was conducted at the International Rice Research Institute, Philippines, in 2010 – 2011 using a temperature free-air controlled enhancement (T-FACE) system. Our object...

  7. Effect of timing of joint application of hydroquinone and dicyandiamide on nitrous oxide emission from irrigated lowland rice paddy field.

    PubMed

    Li, Xianglan; Zhang, Guangbin; Xu, Hua; Cai, Zucong; Yagi, Kazuyuki

    2009-06-01

    A field experiment was conducted to study the effect of timing of joint application of urease inhibitor hydroquinone (HQ) and nitrification inhibitor dicyandiamide (DCD) on N(2)O emission from irrigated lowland rice paddy field. Four treatments including Treatment CK (the control with urea alone), HQ/DCD-1 (application of HQ and DCD together with fertilizer before transplanting), HQ/DCD-2 (HQ and DCD with fertilizer at tillering stage) and HQ/DCD-3 (HQ and DCD with fertilizer at panicle initiation stage) were designed and implemented separately during rice growth period. Seasonal peaks of N(2)O flux occurred during midseason drainage and significant negative correlation between N(2)O flux and water layer depth was observed (r=-0.69 to -0.75, P<0.01). Mean N(2)O flux was the highest in the control with urea alone, while joint addition of HQ and DCD with urea lowered mean N(2)O flux considerably (P<0.05). Total N(2)O emission during rice growth season in Treatment CK, HQ/DCD-1, HQ/DCD-2 and HQ/DCD-3 was 3.90, 2.98, 1.73 and 3.23kgN(2)O-N ha(-1), respectively. Application of HQ and DCD together with basal fertilizer, tillering fertilizer and panicle initiation fertilizer decreased the total N(2)O emission by 24%, 56% and 17%, respectively, while increased grain yield by 10%, 18% and 6%, respectively. Effect of application of inhibitors on N(2)O emission during the continuous period from incorporation of HQ and DCD to rice harvest was also studied, where results indicating that the highest inhibiting efficiency of inhibitors on N(2)O emission was recorded when HQ and DCD applied with fertilizer at tillering stage.

  8. Improving salt tolerance of lowland rice cultivar 'Rassi' through marker-aided backcross breeding in West Africa.

    PubMed

    Bimpong, Isaac Kofi; Manneh, Baboucarr; Sock, Mamadou; Diaw, Faty; Amoah, Nana Kofi Abaka; Ismail, Abdelbagi M; Gregorio, Glenn; Singh, Rakesh Kumar; Wopereis, Marco

    2016-01-01

    Salt stress affects about 25% of the 4.4 million ha of irrigated and lowland systems for rice cultivation in West Africa (WA). A major quantitative trait locus (QTLs) on chromosome 1 (Saltol) that enhances tolerance to salt stress at the vegetative stage has enabled the use of marker-assisted selection (MAS) to develop salt-tolerant rice cultivar(s) in WA. We used 3 cycles of backcrossing with selection based on DNA markers and field-testing using 'FL478' as tolerant donor and the widely grown 'Rassi' as recurrent parent. In the BC3F2 stage, salt-tolerant lines with over 80% Rassi alleles except in the region around Saltol segment were selected. 429 introgression lines (Saltol-ILs) were identified as tolerant at vegetative stage, of which 116 were field-tested for four seasons at the reproductive stage. Sixteen Saltol-ILs had less yield loss (3-26% relative to control trials), and 8 Saltol-ILs showed high yield potential under stress and non-stress conditions. The 16 Saltol-ILs had been included for further African-wide testing prior to release in 6 WA countries. MAS reduced the time for germplasm improvement from at least 7 to about 4 years. Our objective is to combine different genes/QTLs conferring tolerance to stresses under one genetic background using MAS.

  9. Overexpression of the Rice SUMO E3 Ligase Gene OsSIZ1 in Cotton Enhances Drought and Heat Tolerance, and Substantially Improves Fiber Yields in the Field under Reduced Irrigation and Rainfed Conditions

    PubMed Central

    Mishra, Neelam; Sun, Li; Zhu, Xunlu; Smith, Jennifer; Prakash Srivastava, Anurag; Yang, Xiaojie; Pehlivan, Necla; Esmaeili, Nardana; Luo, Hong; Shen, Guoxin; Jones, Don; Auld, Dick; Burke, John

    2017-01-01

    The Arabidopsis SUMO E3 ligase gene AtSIZ1 plays important roles in plant response to abiotic stresses as loss of function in AtSIZ1 leads to increased sensitivity to drought, heat and salt stresses. Overexpression of the AtSIZ1 rice homolog, OsSIZ1, leads to increased heat and drought tolerance in bentgrass, suggesting that the function of the E3 ligase SIZ1 is highly conserved in plants and it plays a critical role in abiotic stress responses. To test the possibility that the SUMO E3 ligase could be used to engineer drought- and heat-tolerant crops, the rice gene OsSIZ1 was overexpressed in cotton. We report here that overexpression of OsSIZ1 in cotton results in higher net photosynthesis and better growth than wild-type cotton under drought and thermal stresses in growth chamber and greenhouse conditions. Additionally, this tolerance to abiotic stresses was correlated with higher fiber yield in both controlled-environment and field trials carried out under reduced irrigation and rainfed conditions. These results suggest that OsSIZ1 is a viable candidate gene to improve crop yields under water-limited and rainfed agricultural production systems. PMID:28340002

  10. Localized Flux Maxima of Arsenic, Lead, and Iron around Root Apices in Flooded Lowland Rice

    PubMed Central

    2014-01-01

    In wetland-adapted plants, such as rice, it is typically root apexes, sites of rapid entry for water/nutrients, where radial oxygen losses (ROLs) are highest. Nutrient/toxic metal uptake therefore largely occurs through oxidized zones and pH microgradients. However, the processes controlling the acquisition of trace elements in rice have been difficult to explore experimentally because of a lack of techniques for simultaneously measuring labile trace elements and O2/pH. Here, we use new diffusive gradients in thin films (DGT)/planar optode sandwich sensors deployed in situ on rice roots to demonstrate a new geochemical niche of greatly enhanced As, Pb, and Fe(II) mobilization into solution immediately adjacent to the root tips characterized by O2 enrichment and low pH. Fe(II) mobilization was congruent to that of the peripheral edge of the aerobic root zone, demonstrating that the Fe(II) mobilization maximum only developed in a narrow O2 range as the oxidation front penetrates the reducing soil. The Fe flux to the DGT resin at the root apexes was 3-fold higher than the anaerobic bulk soil and 27 times greater than the aerobic rooting zone. These results provide new evidence for the importance of coupled diffusion and oxidation of Fe in modulating trace metal solubilization, dispersion, and plant uptake. PMID:24967508

  11. Adaptation to flooding in upland and lowland ecotypes of Cyperus rotundus, a troublesome sedge weed of rice: tuber morphology and carbohydrate metabolism

    PubMed Central

    Peña-Fronteras, Jennifer T.; Villalobos, Mizpah C.; Baltazar, Aurora M.; Merca, Florinia E.; Ismail, Abdelbagi M.; Johnson, David E.

    2009-01-01

    Background and aims In recent years, Cyperus rotundus has become a problem weed in lowland rice (Oryza sativa) grown in rotation with vegetables in the Philippines. As the growth of C. rotundus is commonly suppressed by prolonged flooding, the ability of the weed to grow vigorously in flooded as well as upland conditions suggests that adapted ecotypes occur in these rotations. Studies were conducted to elucidate the mechanisms that permit C. rotundus to tolerate flooded soil conditions. Methods Upland and lowland ecotypes of C. rotundus were compared in terms of growth habit, carbohydrate reserves and metabolism, and activities of enzymes involved in alcoholic fermentation – alcohol dehydrogenase (ADH) and pyruvate decarboxylase (PDC). Key Results The lowland ecotype has much larger tubers than the upland ecotype. Prior to germination, the amylase activity and total non-structural carbohydrate content in the form of soluble sugars were greater in the tubers of lowland plants than in those of upland C. rotundus. At 24 h after germination in hypoxic conditions, PDC and ADH activities in the lowland plants increased, before decreasing at 48 h following germination. In contrast, ADH and PDC activities in the upland plants increased from 24 to 48 h after germination. Conclusions Tolerance of lowland C. rotundus of flooding may be attributed to large carbohydrate content and amylase activity, and the ability to maintain high levels of soluble sugars in the tubers during germination and early growth. This is coupled with the modulation of ADH and PDC activities during germination, possibly to control the use of carbohydrate reserves and sustain substrate supply in order to avoid starvation and death of seedlings with prolonged flooding. PMID:18515404

  12. Improving Lowland Rice (O. sativa L. cv. MR219) Plant Growth Variables, Nutrients Uptake, and Nutrients Recovery Using Crude Humic Substances

    PubMed Central

    Palanivell, Perumal; Ahmed, Osumanu Haruna; Ab Majid, Nik Muhamad; Jalloh, Mohamadu Boyie; Susilawati, Kasim

    2015-01-01

    High cation exchange capacity and organic matter content of crude humic substances from compost could be exploited to reduce ammonia loss from urea and to as well improve rice growth and soil chemical properties for efficient nutrients utilization in lowland rice cultivation. Close-dynamic air flow system was used to determine the effects of crude humic substances on ammonia volatilization. A pot experiment was conducted to determine the effects of crude humic substances on rice plant growth, nutrients uptake, nutrients recovery, and soil chemical properties using an acid soil mixed with three rates of crude humic substances (20, 40, and 60 g pot−1). Standard procedures were used to evaluate rice plant dry matter production, nutrients uptake, nutrients recovery, and soil chemical properties. Application of crude humic substances increased ammonia volatilization. However, the lowest rate of crude humic substances (20 g pot−1) significantly improved total dry matter, nutrients uptake, nutrients recovery, and soil nutrients availability compared with crude humic substances (40 and 60 g pot−1) and the normal fertilization. Apart from improving growth of rice plants, crude humic substances can be used to ameliorate acid soils in rice cultivation. The findings of this study are being validated in our ongoing field trials. PMID:25977938

  13. Improving Lowland Rice (O. sativa L. cv. MR219) Plant Growth Variables, Nutrients Uptake, and Nutrients Recovery Using Crude Humic Substances.

    PubMed

    Palanivell, Perumal; Ahmed, Osumanu Haruna; Ab Majid, Nik Muhamad; Jalloh, Mohamadu Boyie; Susilawati, Kasim

    2015-01-01

    High cation exchange capacity and organic matter content of crude humic substances from compost could be exploited to reduce ammonia loss from urea and to as well improve rice growth and soil chemical properties for efficient nutrients utilization in lowland rice cultivation. Close-dynamic air flow system was used to determine the effects of crude humic substances on ammonia volatilization. A pot experiment was conducted to determine the effects of crude humic substances on rice plant growth, nutrients uptake, nutrients recovery, and soil chemical properties using an acid soil mixed with three rates of crude humic substances (20, 40, and 60 g pot(-1)). Standard procedures were used to evaluate rice plant dry matter production, nutrients uptake, nutrients recovery, and soil chemical properties. Application of crude humic substances increased ammonia volatilization. However, the lowest rate of crude humic substances (20 g pot(-1)) significantly improved total dry matter, nutrients uptake, nutrients recovery, and soil nutrients availability compared with crude humic substances (40 and 60 g pot(-1)) and the normal fertilization. Apart from improving growth of rice plants, crude humic substances can be used to ameliorate acid soils in rice cultivation. The findings of this study are being validated in our ongoing field trials.

  14. QTL mapping of root traits in a doubled haploid population from a cross between upland and lowland japonica rice in three environments.

    PubMed

    Li, Zichao; Mu, Ping; Li, Chunping; Zhang, Hongliang; Li, Zhikang; Gao, Yongming; Wang, Xiangkun

    2005-05-01

    To genetically dissect drought resistance associated with japonica upland rice, we evaluated a doubled haploid (DH) population from a cross between two japonica cultivars for seven root traits under three different growing conditions (upland, lowland and upland in PVC pipe). The traits included basal root thickness (BRT), total root number (RN), maximum root length (MRL), root fresh weight (RFW), root dry weight (RDW), ratio of root fresh weight to shoot fresh weight (RFW/SFW) and ratio of root dry weight to shoot dry weight (RDW/SDW). The BRT was significantly correlated with the index of drought resistance, which was defined as the ratio of yield under the stress of the upland condition to that under the normal lowland condition. A complete genetic linkage map with 165 molecular markers covering 1,535 cM was constructed. Seven additive quantitative trait loci (QTLs) and 15 pairs of epistatic loci for BRT and RN were identified under upland and lowland conditions, and 12 additive QTLs and 17 pairs of epistatic QTLs for BRT, RN, MRL, RFW, RFW/SFW and RDW/SDW were identified under the PVC pipe condition. Four additive QTLs and one pair of epistatic QTLs controlling IDR were also found. These QTLs individually explained up to 25.6% of the phenotypic variance. QTL x environment (Q x E) interactions were detected for all root traits, and the contributions of these interactions ranged from 1.1% to 19.9%. Five co-localized QTLs controlling RFW and RDW, RFW/SFW, RDW/SDW and IDR, BRT and RN, RN, MRL and IDR were found. Four types of QTLs governing BRT and RN were classified by their detection in the upland and lowland conditions. Some common QTLs for root traits across different backgrounds were also revealed. These co-localized QTLs and common QTLs will facilitate marker-assisted selection for root traits in rice breeding programs.

  15. Physiological and molecular responses of seedlings of an upland rice ('Tung Lu 3') to total submergence compared to those of a submergence-tolerant lowland rice ('FR13A').

    PubMed

    Yang, Si-Yu; Wu, Yu-Sian; Chen, Chung-Tse; Lai, Ming-Hsin; Yen, Hsing-Mu; Yang, Chin-Ying

    2017-08-31

    Understanding the responses of rice to environmental stresses such as unscheduled submergence is of pressing important owing to increasing severity of weather thought to arise from global climate change. When rice is completely submerged, different types adopt either a quiescence survival strategy (i.e., minimal shoot elongation) or an escape strategy (i.e., enhanced shoot elongation). Each strategy can prolong survival depending on the circumstances. While submergence responses have been studied in rice typical of lowland and flood-prone areas, few studies have explored the physiological and molecular properties of upland rice under submergence. Here, we use seedlings of the upland rice 'Tung Lu 3' ('TL3') to analyze physiological and molecular responses to submergence. We compare them with those of 'FR13A', a lowland rice that tolerates submergence by adopting the quiescence strategy. Plant height and distance between leaf sheaths, increased rapidly in 'TL3' under submergence. Although this indicated a strong escape strategy the seedlings remained totally underwater for the duration of the experiments. In contrast, 'FR13A' elongated much less. Consequently, after 4 days complete submergence followed by drainage, 'TL3' lodged much more severely than 'FR13A'. After 10 d complete submergence, 55% of 'TL3' seedlings survived compared to 100% in 'FR13A'. Chlorophyll a, b and total chlorophyll concentrations of the 2(nd) oldest leaves of 'TL3' were also significantly above those of 'FR13A' (but were lower than 'FR13A' in the 3(rd) oldest leaves) and less hydrogen peroxide accumulated in 'TL3'. Peroxidase activity in submerged 'TL3' was also greater than in 'FR13A' 1 day after submergence. Quantitative RT-PCR showed increased expression of sucrose synthase 1 and alcohol dehydrogenases 1 after 2 days complete submergence with significantly higher levels in 'TL3' compared to 'FR13A'. Expression was also higher in 'TL3' under non-submerged conditions. The upland rice

  16. Origin, dispersal, cultivation and variation of rice.

    PubMed

    Khush, G S

    1997-09-01

    There are two cultivated and twenty-one wild species of genus Oryza. O. sativa, the Asian cultivated rice is grown all over the world. The African cultivated rice, O. glaberrima is grown on a small scale in West Africa. The genus Oryza probably originated about 130 million years ago in Gondwanaland and different species got distributed into different continents with the breakup of Gondwanaland. The cultivated species originated from a common ancestor with AA genome. Perennial and annual ancestors of O. sativa are O. rufipogon and O. nivara and those of O. glaberrima are O. longistaminata, O. breviligulata and O. glaberrima probably domesticated in Niger river delta. Varieties of O. sativa are classified into six groups on the basis of genetic affinity. Widely known indica rices correspond to group I and japonicas to group VI. The so called javanica rices also belong to group VI and are designated as tropical japonicas in contrast to temperate japonicas grown in temperate climate. Indica and japonica rices had a polyphyletic origin. Indicas were probably domesticated in the foothills of Himalayas in Eastern India and japonicas somewhere in South China. The indica rices dispersed throughout the tropics and subtropics from India. The japonica rices moved northward from South China and became the temperate ecotype. They also moved southward to Southeast Asia and from there to West Africa and Brazil and became tropical ecotype. Rice is now grown between 55 degrees N and 36 degrees S latitudes. It is grown under diverse growing conditions such as irrigated, rainfed lowland, rainfed upland and floodprone ecosystems. Human selection and adaptation to diverse environments has resulted in numerous cultivars. It is estimated that about 120,000 varieties of rice exist in the world. After the establishment of International Rice Research Institute in 1960, rice varietal improvement was intensified and high yielding varieties were developed. These varieties are now planted to 70

  17. Habitat manipulation in lowland rice-coconut cropping systems of the Philippines--an effective rodent pest management strategy?

    PubMed

    Stuart, Alexander M; Prescott, Colin V; Singleton, Grant R

    2014-06-01

    Reduction of vegetation height is recommended as a management strategy for controlling rodent pests of rice in South-east Asia, but there are limited field data to assess its effectiveness. The breeding biology of the main pest species of rodent in the Philippines, Rattus tanezumi, suggests that habitat manipulation in irrigated rice-coconut cropping systems may be an effective strategy to limit the quality and availability of their nesting habitat. The authors imposed a replicated manipulation of vegetation cover in adjacent coconut groves during a single rice-cropping season, and added artificial nest sites to facilitate capture and culling of young. Three trapping sessions in four rice fields (two treatments, two controls) adjacent to coconut groves led to the capture of 176 R. tanezumi, 12 Rattus exulans and seven Chrotomys mindorensis individuals. There was no significant difference in overall abundance between crop stages or between treatments, and there was no treatment effect on damage to tillers or rice yield. Only two R. tanezumi were caught at the artificial nest sites. Habitat manipulation to reduce the quality of R. tanezumi nesting habitat adjacent to rice fields is not effective as a lone rodent management tool in rice-coconut cropping systems. © 2013 Society of Chemical Industry.

  18. Rainfed Areas and Animal Agriculture in Asia: The Wanting Agenda for Transforming Productivity Growth and Rural Poverty

    PubMed Central

    Devendra, C.

    2012-01-01

    The importance of rainfed areas and animal agriculture on productivity enhancement and food security for economic rural growth in Asia is discussed in the context of opportunities for increasing potential contribution from them. The extent of the rainfed area of about 223 million hectares and the biophysical attributes are described. They have been variously referred to inter alia as fragile, marginal, dry, waste, problem, threatened, range, less favoured, low potential lands, forests and woodlands, including lowlands and uplands. Of these, the terms less favoured areas (LFAs), and low or high potential are quite widely used. The LFAs are characterised by four key features: i) very variable biophysical elements, notably poor soil quality, rainfall, length of growing season and dry periods, ii) extreme poverty and very poor people who continuously face hunger and vulnerability, iii) presence of large populations of ruminant animals (buffaloes, cattle, goats and sheep), and iv) have had minimum development attention and an unfinished wanting agenda. The rainfed humid/sub-humid areas found mainly in South East Asia (99 million ha), and arid/semi-arid tropical systems found in South Asia (116 million ha) are priority agro-ecological zones (AEZs). In India for example, the ecosystem occupies 68% of the total cultivated area and supports 40% of the human and 65% of the livestock populations. The area also produces 4% of food requirements. The biophysical and typical household characteristics, agricultural diversification, patterns of mixed farming and cropping systems are also described. Concerning animals, their role and economic importance, relevance of ownership, nomadic movements, and more importantly their potential value as the entry point for the development of LFAs is discussed. Two examples of demonstrated success concern increasing buffalo production for milk and their expanded use in semi-arid AEZs in India, and the integration of cattle and goats with oil

  19. Rainfed areas and animal agriculture in Asia: the wanting agenda for transforming productivity growth and rural poverty.

    PubMed

    Devendra, C

    2012-01-01

    The importance of rainfed areas and animal agriculture on productivity enhancement and food security for economic rural growth in Asia is discussed in the context of opportunities for increasing potential contribution from them. The extent of the rainfed area of about 223 million hectares and the biophysical attributes are described. They have been variously referred to inter alia as fragile, marginal, dry, waste, problem, threatened, range, less favoured, low potential lands, forests and woodlands, including lowlands and uplands. Of these, the terms less favoured areas (LFAs), and low or high potential are quite widely used. The LFAs are characterised by four key features: i) very variable biophysical elements, notably poor soil quality, rainfall, length of growing season and dry periods, ii) extreme poverty and very poor people who continuously face hunger and vulnerability, iii) presence of large populations of ruminant animals (buffaloes, cattle, goats and sheep), and iv) have had minimum development attention and an unfinished wanting agenda. The rainfed humid/sub-humid areas found mainly in South East Asia (99 million ha), and arid/semi-arid tropical systems found in South Asia (116 million ha) are priority agro-ecological zones (AEZs). In India for example, the ecosystem occupies 68% of the total cultivated area and supports 40% of the human and 65% of the livestock populations. The area also produces 4% of food requirements. The biophysical and typical household characteristics, agricultural diversification, patterns of mixed farming and cropping systems are also described. Concerning animals, their role and economic importance, relevance of ownership, nomadic movements, and more importantly their potential value as the entry point for the development of LFAs is discussed. Two examples of demonstrated success concern increasing buffalo production for milk and their expanded use in semi-arid AEZs in India, and the integration of cattle and goats with oil

  20. Adaptation to flooding during emergence and seedling growth in rice and weeds, and implications for crop establishment.

    PubMed

    Ismail, Abdelbagi M; Johnson, David E; Ella, Evangelina S; Vergara, Georgina V; Baltazar, Aurora M

    2012-01-01

    Direct seeding of rice is being adopted in rainfed and irrigated lowland ecosystems because it reduces labour costs in addition to other benefits. However, early flooding due to uneven fields or rainfall slows down seed germination and hinders crop establishment. Conversely, early flooding helps suppress weeds and reduces the costs of manual weeding and/or dependence on herbicides; however, numerous weed species are adapted to lowlands and present challenges for the use of flooding to control weeds. Advancing knowledge on the mechanisms of tolerance of flooding during germination and early growth in rice and weeds could facilitate the development of improved rice varieties and effective weed management practices for direct-seeded rice. Rice genotypes with a greater ability to germinate and establish in flooded soils were identified, providing opportunities to develop varieties suitable for direct seeding in flooded soils. Tolerance of flooding in these genotypes was mostly attributed to traits associated with better ability to mobilize stored carbohydrates and anaerobic metabolism. Limited studies were undertaken in weeds associated with lowland rice systems. Remaining studies compared rice and weeds and related weed species such as Echinochloa crus-galli and E. colona or compared ecotypes of the same species of Cyperus rotundus adapted to either aerobic or flooded soils. Tolerant weeds and rice genotypes mostly developed similar adaptive traits that allow them to establish in flooded fields, including the ability to germinate and elongate faster under hypoxia, mobilize stored starch reserves and generate energy through fermentation pathways. Remarkably, some weeds developed additional traits such as larger storage tubers that enlarge further in deeper flooded soils (C. rotundus). Unravelling the mechanisms involved in adaptation to flooding will help design management options that will allow tolerant rice genotypes to adequately establish in flooded soils while

  1. Adaptation to flooding during emergence and seedling growth in rice and weeds, and implications for crop establishment

    PubMed Central

    Ismail, Abdelbagi M.; Johnson, David E.; Ella, Evangelina S.; Vergara, Georgina V.; Baltazar, Aurora M.

    2012-01-01

    Background and aims Direct seeding of rice is being adopted in rainfed and irrigated lowland ecosystems because it reduces labour costs in addition to other benefits. However, early flooding due to uneven fields or rainfall slows down seed germination and hinders crop establishment. Conversely, early flooding helps suppress weeds and reduces the costs of manual weeding and/or dependence on herbicides; however, numerous weed species are adapted to lowlands and present challenges for the use of flooding to control weeds. Advancing knowledge on the mechanisms of tolerance of flooding during germination and early growth in rice and weeds could facilitate the development of improved rice varieties and effective weed management practices for direct-seeded rice. Principal results Rice genotypes with a greater ability to germinate and establish in flooded soils were identified, providing opportunities to develop varieties suitable for direct seeding in flooded soils. Tolerance of flooding in these genotypes was mostly attributed to traits associated with better ability to mobilize stored carbohydrates and anaerobic metabolism. Limited studies were undertaken in weeds associated with lowland rice systems. Remaining studies compared rice and weeds and related weed species such as Echinochloa crus-galli and E. colona or compared ecotypes of the same species of Cyperus rotundus adapted to either aerobic or flooded soils. Conclusions Tolerant weeds and rice genotypes mostly developed similar adaptive traits that allow them to establish in flooded fields, including the ability to germinate and elongate faster under hypoxia, mobilize stored starch reserves and generate energy through fermentation pathways. Remarkably, some weeds developed additional traits such as larger storage tubers that enlarge further in deeper flooded soils (C. rotundus). Unravelling the mechanisms involved in adaptation to flooding will help design management options that will allow tolerant rice genotypes

  2. Alternate wetting and drying irrigation maintained rice yields despite half the irrigation volume, but is currently unlikely to be adopted by smallholder lowland rice farmers in Nepal.

    PubMed

    Howell, Katharine R; Shrestha, Pitambar; Dodd, Ian C

    2015-07-01

    Alternate wetting and drying (AWD) irrigation can save water while maintaining rice yields, but in some countries its adoption by farmers remains limited. Key knowledge gaps include the effect of AWD on early vegetative vigor and its relationship with yield; the effects of AWD on yield and water use efficiency of local cultivars used by smallholder farmers; and the socio-economic factors influencing current irrigation scheduling. To address these questions, an on-farm field trial of dry-season (chaite) rice, comparing two locally important cultivars (Hardinath-1 and CH-45) under AWD imposed from 1 week after transplanting to flowering and continuous flooding (CF), was carried out in Agyauli in the central Terai region of Nepal, and triangulated with social research methods exploring the rationale for current irrigation scheduling and perceptions of AWD. Although AWD plots received on average 57% less irrigation water than CF plots, yields did not significantly differ between irrigation treatments, indicating that AWD could considerably enhance crop water use efficiency in this region. In the earlier flowering, more vigorous CH-45, there were no treatment differences in any yield component while in the later flowering Hardinath-1, an 11% decrease in filled grain number was compensated by a 14% increase in the percentage of effective tillers per hill. Although leaf elongation rate on the main tiller did not differ between treatments, tillering and green fraction (a measure of canopy closure) were significantly higher under AWD. Surveys established that most local farmers are already using a local adaptation of AWD to modify irrigation volumes, in some cases in response to a limited and unreliable water supply. However, farmers have few direct incentives to reduce overall water use under current water governance, and formal AWD practices are therefore unlikely to be adopted despite their viability as a water-saving irrigation technique.

  3. Silicon alleviates drought stress of rice plants by improving plant water status, photosynthesis and mineral nutrient absorption.

    PubMed

    Chen, Wei; Yao, Xiaoqin; Cai, Kunzheng; Chen, Jining

    2011-07-01

    Drought is a major constraint for rice production in the rainfed lowlands in China. Silicon (Si) has been verified to play an important role in enhancing plant resistance to environmental stress. Two near-isogenic lines of rice (Oryza sativa L.), w-14 (drought susceptible) and w-20 (drought resistant), were selected to study the effects of exogenous Si application on the physiological traits and nutritional status of rice under drought stress. In wet conditions, Si supply had no effects on growth and physiological parameters of rice plants. Drought stress was found to reduce dry weight, root traits, water potential, photosynthetic parameters, basal quantum yield (F(v)/F(0)), and maximum quantum efficiency of PSII photochemistry (F(v)/F(m)) in rice plants, while Si application significantly increased photosynthetic rate (Pr), transpiration rate (Tr), F(v)/F(0), and F(v)/F(m) of rice plants under drought stress. In addition, water stress increased K, Na, Ca, Mg, Fe content of rice plants, but Si treatment significantly reduced these nutrient level. These results suggested that silicon application was useful to increase drought resistance of rice through the enhancement of photochemical efficiency and adjustment of the mineral nutrient absorption in rice plants.

  4. Phenotypic and genetic diversity of rice seed-associated bacteria and their role in pathogenicity and biological control.

    PubMed

    Cottyn, B; Debode, J; Regalado, E; Mew, T W; Swings, J

    2009-09-01

    To study the phenotypic and genetic diversity of culturable bacteria associated with rice seed and to asses the antagonistic and pathogenic potential of the isolated bacteria. Seed of rice cultivar PSBRc14 was collected from farmers' fields of irrigated lowland in southern Luzon, Philippines. Isolations of distinct colonies yielded 498 isolates. Classification of the isolates according to similarities in cellular characteristics, whole-cell fatty acid composition, and colony appearance differentiated 101 morphotype groups. Predominant bacteria were Coryneform spp., Pantoea spp. and Pseudomonas spp. Other bacteria regularly present were Actinomycetes spp., Bacillus pumilus, B. subtilis, Burkholderia glumae, Enterobacter cloacae, Paenibacillus polymyxa, Staphylococcus spp. and Xanthomonas spp. The genetic diversity among isolates was assessed by BOX-PCR fingerprinting of genomic DNA and represented 284 fingerprint types (FPTs). Most FPTs (78%) were not shared among samples, while eight FPTs occurred frequently in the samples. Seven of these FPTs also occurred frequently in a previous collection made from rainfed lowlands of Iloilo island, Philippines. Sixteen per cent of the isolates inhibited in vitro the mycelial growth of the rice pathogens Rhizoctonia solani and Pyricularia grisea, whereas 4% were pathogens identified as Burkholderia glumae, Burkholderia gladioli and Acidovorax avenae ssp. avenae. This study reveals a broad morphological and genetic diversity of bacteria present on seed of a single rice cultivar. This line of work contributes to a better understanding of the microbial diversity present on rice seed and stresses its importance as a carrier of antagonists and pathogens.

  5. Comparative Transcriptional Profiling of Primed and Non-primed Rice Seedlings under Submergence Stress

    PubMed Central

    Hussain, Saddam; Yin, Hanqi; Peng, Shaobing; Khan, Faheem A.; Khan, Fahad; Sameeullah, Muhammad; Hussain, Hafiz A.; Huang, Jianliang; Cui, Kehui; Nie, Lixiao

    2016-01-01

    Submergence stress is a limiting factor for direct-seeded rice systems in rainfed lowlands and flood-prone areas of South and Southeast Asia. The present study demonstrated that submergence stress severely hampered the germination and seedling growth of rice, however, seed priming alleviated the detrimental effects of submergence stress. To elucidate the molecular basis of seed priming-induced submergence tolerance, transcriptome analyses were performed using 4-day-old primed (selenium-Se and salicylic acid-SA priming) and non-primed rice seedlings under submergence stress. Genomewide transcriptomic profiling identified 2371 and 2405 transcripts with Se- and SA-priming, respectively, that were differentially expressed in rice compared with non-priming treatment under submergence. Pathway and gene ontology term enrichment analyses revealed that genes involved in regulation of secondary metabolism, development, cell, transport, protein, and metal handling were over-represented after Se- or SA-priming. These coordinated factors might have enhanced the submergence tolerance and maintained the better germination and vigorous seedling growth of primed rice seedlings. It was also found that many genes involved in cellular and metabolic processes such as carbohydrate metabolism, cellular, and metabolic biosynthesis, nitrogen compound metabolic process, transcription, and response to oxidative stress were induced and overlapped in seed priming treatments, a finding which reveals the common mechanism of seed priming-induced submergence tolerance. Taken together, these results may provide new avenues for understanding and advancing priming-induced responses to submergence tolerance in crop plants. PMID:27516766

  6. LANDSCAPE CHANGES IN A LOWLAND IN BENIN: ECOLOGICAL IMPACT ON PESTS AND NATURAL ENEMIES.

    PubMed

    Boucher, A; Silvie, P; Menozzi, P; Adda, C; Auzoux, S; Jean, J; Huat, J

    2015-01-01

    Habitat management involving conservative biological control could be a good crop pest management option in poor African countries. A survey was conducted from August 2013 to July 2014 in a rainfed lowland region near Pélébina, northern Benin, in order to characterize spatiotemporal landscape changes and investigate their influence on the main crop pests and their associated natural enemies. The area was mapped mainly regarding crop fields and fallows. Visual observations were recorded and a database was compiled. Major landscape composition changes were noted between rainy and dry seasons, which affected the presence of both pests and natural enemies. Cereals (rice, maize and sorghum) and cotton were grown in the humid season, and then okra (Abelmoschus esculentus) was the dominant vegetable crop in dry season. These modifications impacted fallow abundance throughout the lowland. Different cotton (e.g. Helicoverpa armigera, Dysdercus sp., Zonocerus variegatus) or rice (e.g. Diopsis longicornis, D. apicalis) pests were observed during dry season in okra crops. Dry season surveys of Poaceae in two types of fallows ('humid', 'dry') revealed the presence of very few stem borers: only 0.04% of stems sampled were infested by stem borers, with a mean of 1.13 larvae per stem. Known cereal stem borer species such as Busseola fusco, Coniesta ignefusalis, Sesamia calamistis were not clearly identified among these larvae because of their diapausing stage and white color. Unexpected pollinators (Hymenoptera Apidae, genus Braunsapis, Ceratina and Xylocopa) and predators (Crabronidae, genus Dasyproctus) were found in the stems. Sweep-net collection of insects in humid fallows allowed us to describe for the first time in Benin seven Diopsidae species (23% of adults bearing Laboulbeniomycetes ectoparasitic fungi). Some of these species were captured in rice fields during rainy season. Parasitoids (adult Chalcidoidae and Ichneumonoidae) were observed during both seasons but their

  7. Effects of water-saving irrigation practices and drought resistant rice variety on greenhouse gas emissions from a no-till paddy in the central lowlands of China.

    PubMed

    Xu, Ying; Ge, Junzhu; Tian, Shaoyang; Li, Shuya; Nguy-Robertson, Anthony L; Zhan, Ming; Cao, Cougui

    2015-02-01

    As pressure on water resources increases, alternative practices to conserve water in paddies have been developed. Few studies have simultaneously examined the effectiveness of different water regimes on conserving water, mitigating greenhouse gases (GHG), and maintaining yields in rice production. This study, which was conducted during the drought of 2013, examined all three factors using a split-plot experiment with two rice varieties in a no-till paddy managed under three different water regimes: 1) continuous flooding (CF), 2) flooded and wet intermittent irrigation (FWI), and 3) flooded and dry intermittent irrigation (FDI). The Methane (CH₄) and nitrous oxide (N₂O) emissions were measured using static chamber-gas measurements, and the carbon dioxide (CO₂) emissions were monitored using a soil CO₂ flux system (LI-8100). Compared with CF, FWI and FDI irrigation strategies reduced CH₄ emissions by 60% and 83%, respectively. In contrast, CO₂ and N₂O fluxes increased by 65% and 9%, respectively, under FWI watering regime and by 104% and 11%, respectively, under FDI managed plots. Although CO₂ and N₂O emissions increased, the global warming potential (GWP) and greenhouse gas intensity (GHGI) of all three GHG decreased by up to 25% and 29% (p<0.01), respectively, using water-saving irrigation strategies. The rice variety also affected yields and GHG emissions in response to different water regimes. The drought-resistance rice variety (HY3) was observed to maintain yields, conserve water, and reduce GHG under the FWI irrigation management compared with the typical variety (FYY299) planted in the region. The FYY299 only had significantly lower GWP and GHGI when the yield was reduced under FDI water regime. In conclusion, FWI irrigation strategy could be an effective option for simultaneously saving water and mitigating GWP without reducing rice yields using drought-resistant rice varieties, such as HY3. Copyright © 2014 Elsevier B.V. All rights

  8. Physiological and Molecular Basis of Susceptibility and Tolerance of Rice Plants to Complete Submergence

    PubMed Central

    JACKSON, MICHAEL B.; RAM, PHOOL C.

    2003-01-01

    Rice plants are much damaged by several days of total submergence. The effect can be a serious problem for rice farmers in the rainfed lowlands of Asia, and runs contrary to a widespread belief amongst plant biologists that rice is highly tolerant of submergence. This article assesses the characteristics of the underwater environment that may damage rice plants, examines various physiological mechanisms of injury, and reviews recent progress achieved using linkage mapping to locate quantitative traits loci (QTL) for tolerance inherited from a submergence‐tolerant cultivar FR13A. Progress towards identifying the gene(s) involved through physical mapping of a dominant tolerance locus on chromosome 9 is also summarized. Available physiological evidence points away from responses to oxygen shortage as being inextricably involved in submergence injury. An imbalance between production and consumption of assimilates is seen as being especially harmful, and is exacerbated by strongly accelerated leaf extension and leaf senescence that are ethylene‐mediated and largely absent from FR13A and related cultivars. DNA markers for a major QTL for tolerance are shown to be potentially useful in breeding programmes designed to improve submergence tolerance. PMID:12509343

  9. Morphological and physiological responses of rice seedlings to complete submergence (flash flooding)

    PubMed Central

    Kawano, Naoyoshi; Ito, Osamu; Sakagami, Jun-Ichi

    2009-01-01

    Background and Aims Reducing damage to rice seedlings caused by flash flooding will improve the productivity of rainfed lowland rice in West Africa. Accordingly, the morphological and physiological responses of different forms of rice to complete submergence were examined in field and pot experiments to identify primary causes of damage. Methods To characterize the physiological responses, seedlings from a wide genetic base including Oryza sativa, O. glaberrima and interspecific hybrids were compared using principle component analysis. Key Results Important factors linked to flash-flood tolerance included minimal shoot elongation underwater, increase in dry matter weight during submergence and post-submergence resistance to lodging. In particular, fast shoot elongation during submergence negatively affected plant growth after de-submergence. Also shoot-elongating cultivars showed a strong negative correlation between dry matter weight of the leaves that developed before submergence and leaves developing during submergence. Conclusions Enhancement of shoot elongation during submergence in water that is too deep to permit re-emergence by small seedlings represents a futile escape strategy that takes place at the expense of existing dry matter in circumstances where underwater photosynthetic carbon fixation is negligible. Consequently, it compromises survival or recovery growth once flood water levels recede and plants are re-exposed to the aerial environment. Tolerance is greater in cultivars where acceleration of elongation caused by submergence is minimal. PMID:18940854

  10. Morphological and physiological responses of rice seedlings to complete submergence (flash flooding).

    PubMed

    Kawano, Naoyoshi; Ito, Osamu; Sakagami, Jun-Ichi

    2009-01-01

    Reducing damage to rice seedlings caused by flash flooding will improve the productivity of rainfed lowland rice in West Africa. Accordingly, the morphological and physiological responses of different forms of rice to complete submergence were examined in field and pot experiments to identify primary causes of damage. To characterize the physiological responses, seedlings from a wide genetic base including Oryza sativa, O. glaberrima and interspecific hybrids were compared using principle component analysis. Important factors linked to flash-flood tolerance included minimal shoot elongation underwater, increase in dry matter weight during submergence and post-submergence resistance to lodging. In particular, fast shoot elongation during submergence negatively affected plant growth after de-submergence. Also shoot-elongating cultivars showed a strong negative correlation between dry matter weight of the leaves that developed before submergence and leaves developing during submergence. Enhancement of shoot elongation during submergence in water that is too deep to permit re-emergence by small seedlings represents a futile escape strategy that takes place at the expense of existing dry matter in circumstances where underwater photosynthetic carbon fixation is negligible. Consequently, it compromises survival or recovery growth once flood water levels recede and plants are re-exposed to the aerial environment. Tolerance is greater in cultivars where acceleration of elongation caused by submergence is minimal.

  11. Field Trials Reveal Ecotype-Specific Responses to Mycorrhizal Inoculation in Rice

    PubMed Central

    Diedhiou, Abdala Gamby; Mbaye, Fatou Kine; Mbodj, Daouda; Faye, Mathieu Ndigue; Pignoly, Sarah; Ndoye, Ibrahima; Djaman, Koffi; Gaye, Souleymane; Kane, Aboubacry; Laplaze, Laurent; Manneh, Baboucarr; Champion, Antony

    2016-01-01

    The overuse of agricultural chemicals such as fertilizer and pesticides aimed at increasing crop yield results in environmental damage, particularly in the Sahelian zone where soils are fragile. Crop inoculation with beneficial soil microbes appears as a good alternative for reducing agricultural chemical needs, especially for small farmers. This, however, requires selecting optimal combinations of crop varieties and beneficial microbes tested in field conditions. In this study, we investigated the response of rice plants to inoculation with arbuscular mycorrhizal fungi (AMF) and plant growth promoting bacteria (PGPB) under screenhouse and field conditions in two consecutive seasons in Senegal. Evaluation of single and mixed inoculations with AMF and PGPB was conducted on rice (Oryza sativa) variety Sahel 202, on sterile soil under screenhouse conditions. We observed that inoculated plants, especially plants treated with AMF, grew taller, matured earlier and had higher grain yield than the non-inoculated plants. Mixed inoculation trials with two AMF strains were then conducted under irrigated field conditions with four O. sativa varieties, two O. glaberrima varieties and two interspecific NERICA varieties, belonging to 3 ecotypes (upland, irrigated, and rainfed lowland). We observed that the upland varieties had the best responses to inoculation, especially with regards to grain yield, harvest index and spikelet fertility. These results show the potential of using AMF to improve rice production with less chemical fertilizers and present new opportunities for the genetic improvement in rice to transfer the ability of forming beneficial rice-microbe associations into high yielding varieties in order to increase further rice yield potentials. PMID:27907023

  12. Field Trials Reveal Ecotype-Specific Responses to Mycorrhizal Inoculation in Rice.

    PubMed

    Diedhiou, Abdala Gamby; Mbaye, Fatou Kine; Mbodj, Daouda; Faye, Mathieu Ndigue; Pignoly, Sarah; Ndoye, Ibrahima; Djaman, Koffi; Gaye, Souleymane; Kane, Aboubacry; Laplaze, Laurent; Manneh, Baboucarr; Champion, Antony

    2016-01-01

    The overuse of agricultural chemicals such as fertilizer and pesticides aimed at increasing crop yield results in environmental damage, particularly in the Sahelian zone where soils are fragile. Crop inoculation with beneficial soil microbes appears as a good alternative for reducing agricultural chemical needs, especially for small farmers. This, however, requires selecting optimal combinations of crop varieties and beneficial microbes tested in field conditions. In this study, we investigated the response of rice plants to inoculation with arbuscular mycorrhizal fungi (AMF) and plant growth promoting bacteria (PGPB) under screenhouse and field conditions in two consecutive seasons in Senegal. Evaluation of single and mixed inoculations with AMF and PGPB was conducted on rice (Oryza sativa) variety Sahel 202, on sterile soil under screenhouse conditions. We observed that inoculated plants, especially plants treated with AMF, grew taller, matured earlier and had higher grain yield than the non-inoculated plants. Mixed inoculation trials with two AMF strains were then conducted under irrigated field conditions with four O. sativa varieties, two O. glaberrima varieties and two interspecific NERICA varieties, belonging to 3 ecotypes (upland, irrigated, and rainfed lowland). We observed that the upland varieties had the best responses to inoculation, especially with regards to grain yield, harvest index and spikelet fertility. These results show the potential of using AMF to improve rice production with less chemical fertilizers and present new opportunities for the genetic improvement in rice to transfer the ability of forming beneficial rice-microbe associations into high yielding varieties in order to increase further rice yield potentials.

  13. Response of Methanogenic Microbial Communities to Desiccation Stress in Flooded and Rain-Fed Paddy Soil from Thailand

    PubMed Central

    Reim, Andreas; Hernández, Marcela; Klose, Melanie; Chidthaisong, Amnat; Yuttitham, Monthira; Conrad, Ralf

    2017-01-01

    Rice paddies in central Thailand are flooded either by irrigation (irrigated rice) or by rain (rain-fed rice). The paddy soils and their microbial communities thus experience permanent or arbitrary submergence, respectively. Since methane production depends on anaerobic conditions, we hypothesized that structure and function of the methanogenic microbial communities are different in irrigated and rain-fed paddies and react differently upon desiccation stress. We determined rates and relative proportions of hydrogenotrophic and aceticlastic methanogenesis before and after short-term drying of soil samples from replicate fields. The methanogenic pathway was determined by analyzing concentrations and δ13C of organic carbon and of CH4 and CO2 produced in the presence and absence of methyl fluoride, an inhibitor of aceticlastic methanogenesis. We also determined the abundance (qPCR) of genes and transcripts of bacterial 16S rRNA, archaeal 16S rRNA and methanogenic mcrA (coding for a subunit of the methyl coenzyme M reductase) and the composition of these microbial communities by T-RFLP fingerprinting and/or Illumina deep sequencing. The abundances of genes and transcripts were similar in irrigated and rain-fed paddy soil. They also did not change much upon desiccation and rewetting, except the transcripts of mcrA, which increased by more than two orders of magnitude. In parallel, rates of CH4 production also increased, in rain-fed soil more than in irrigated soil. The contribution of hydrogenotrophic methanogenesis increased in rain-fed soil and became similar to that in irrigated soil. However, the relative microbial community composition on higher taxonomic levels was similar between irrigated and rain-fed soil. On the other hand, desiccation and subsequent anaerobic reincubation resulted in systematic changes in the composition of microbial communities for both Archaea and Bacteria. It is noteworthy that differences in the community composition were mostly detected

  14. Response of Methanogenic Microbial Communities to Desiccation Stress in Flooded and Rain-Fed Paddy Soil from Thailand.

    PubMed

    Reim, Andreas; Hernández, Marcela; Klose, Melanie; Chidthaisong, Amnat; Yuttitham, Monthira; Conrad, Ralf

    2017-01-01

    Rice paddies in central Thailand are flooded either by irrigation (irrigated rice) or by rain (rain-fed rice). The paddy soils and their microbial communities thus experience permanent or arbitrary submergence, respectively. Since methane production depends on anaerobic conditions, we hypothesized that structure and function of the methanogenic microbial communities are different in irrigated and rain-fed paddies and react differently upon desiccation stress. We determined rates and relative proportions of hydrogenotrophic and aceticlastic methanogenesis before and after short-term drying of soil samples from replicate fields. The methanogenic pathway was determined by analyzing concentrations and δ(13)C of organic carbon and of CH4 and CO2 produced in the presence and absence of methyl fluoride, an inhibitor of aceticlastic methanogenesis. We also determined the abundance (qPCR) of genes and transcripts of bacterial 16S rRNA, archaeal 16S rRNA and methanogenic mcrA (coding for a subunit of the methyl coenzyme M reductase) and the composition of these microbial communities by T-RFLP fingerprinting and/or Illumina deep sequencing. The abundances of genes and transcripts were similar in irrigated and rain-fed paddy soil. They also did not change much upon desiccation and rewetting, except the transcripts of mcrA, which increased by more than two orders of magnitude. In parallel, rates of CH4 production also increased, in rain-fed soil more than in irrigated soil. The contribution of hydrogenotrophic methanogenesis increased in rain-fed soil and became similar to that in irrigated soil. However, the relative microbial community composition on higher taxonomic levels was similar between irrigated and rain-fed soil. On the other hand, desiccation and subsequent anaerobic reincubation resulted in systematic changes in the composition of microbial communities for both Archaea and Bacteria. It is noteworthy that differences in the community composition were mostly

  15. Tolerance of anaerobic conditions caused by flooding during germination and early growth in rice (Oryza sativa L.)

    PubMed Central

    Miro, Berta; Ismail, Abdelbagi M.

    2013-01-01

    Rice is semi-aquatic, adapted to a wide range of hydrologies, from aerobic soils in uplands to anaerobic and flooded fields in waterlogged lowlands, to even deeply submerged soils in flood-prone areas. Considerable diversity is present in native rice landraces selected by farmers over centuries. Our understanding of the adaptive features of these landraces to native ecosystems has improved considerably over the recent past. In some cases, major genes associated with tolerance have been cloned, such as SUB1A that confers tolerance of complete submergence and SNORKEL genes that control plant elongation to escape deepwater. Modern rice varieties are sensitive to flooding during germination and early growth, a problem commonly encountered in rainfed areas, but few landraces capable of germination under these conditions have recently been identified, enabling research into tolerance mechanisms. Major QTLs were also identified, and are being targeted for molecular breeding and for cloning. Nevertheless, limited progress has been made in identifying regulatory processes for traits that are unique to tolerant genotypes, including faster germination and coleoptile elongation, formation of roots and leaves under hypoxia, ability to catabolize starch into simple sugars for subsequent use in glycolysis and fermentative pathways to generate energy. Here we discuss the state of knowledge on the role of the PDC-ALDH-ACS bypass and the ALDH enzyme as the likely candidates effective in tolerant rice genotypes. Potential involvement of factors such as cytoplasmic pH regulation, phytohormones, reactive oxygen species scavenging and other metabolites is also discussed. Further characterization of contrasting genotypes would help in elucidating the genetic and biochemical regulatory and signaling mechanisms associated with tolerance. This could facilitate breeding rice varieties suitable for direct seeding systems and guide efforts for improving waterlogging tolerance in other crops

  16. Morphological and Physiological Responses of Rice (Oryza sativa) to Limited Phosphorus Supply in Aerated and Stagnant Solution Culture

    PubMed Central

    INSALUD, N.; BELL, R. W.; COLMER, T. D.; RERKASEM, B.

    2006-01-01

    • Background and Aims Rain-fed lowland rice commonly encounters stresses from fluctuating water regimes and nutrient deficiency. Roots have to acquire both oxygen and nutrients under adverse conditions while also acclimating to changes in soil-water regime. This study assessed responses of rice roots to low phosphorus supply in aerated and stagnant nutrient solution. • Methods Rice (Oryza sativa ‘Amaroo’) was grown in aerated solution with high P (200 μm) for 14 d, then transferred to high or low (1·6 μm) P supply in aerated or stagnant solution for up to 8 d. • Key Results After only 1 d in stagnant conditions, root radial oxygen loss (ROL) had decreased by 90 % in subapical zones, whereas near the tip ROL was maintained. After 4 d in stagnant conditions, maximum root length was 11 % less, and after 8 d, shoot growth was 25 % less, compared with plants in aerated solution. The plants in stagnant solution had up to 19 % more adventitious roots, 24 % greater root porosity and 26 % higher root/shoot ratio. Rice in low P supply had fewer tillers in both stagnant and aerated conditions. After 1–2 d in stagnant solution, relative P uptake declined, especially at low P supply. Aerated roots at low P supply maintained relative P uptake for 4 d, after which uptake decreased to the same levels as in stagnant solution. • Conclusions Roots responded rapidly to oxygen deficiency with decreased ROL in subapical zones within 1–2 d, indicating induction of a barrier to ROL, and these changes in ROL occurred at least 2 d before any changes in root morphology, porosity or anatomy were evident. Relative P uptake also decreased under oxygen deficiency, showing that a sudden decline in root-zone oxygen adversely affects P nutrition of rice. PMID:17035284

  17. Monsoon variability, crop water requirement, and crop planning for kharif rice in Sagar Island, India

    NASA Astrophysics Data System (ADS)

    Mandal, S.; Choudhury, B. U.; Satpati, L. N.

    2015-12-01

    In the Sagar Island of Bay of Bengal, rainfed lowland rice is the major crop, grown solely depending on erratic distribution of southwest monsoon (SM) rainfall. Lack of information on SM rainfall variability and absence of crop scheduling accordingly results in frequent occurrence of intermittent water stress and occasional crop failure. In the present study, we analyzed long period (1982-2010) SM rainfall behavior (onset, withdrawal, rainfall and wetness indices, dry and wet spells), crop water requirement (CWR, by Food and Agriculture Organization (FAO) 56), and probability of weekly rainfall occurrence (by two-parameter gamma distribution) to assess the variability and impact on water availability, CWR, and rice productivity. Finally, crop planning was suggested to overcome monsoon uncertainties on water availability and rice productivity. Study revealed that the normal onset and withdrawal weeks for SM rainfall were 22nd ± 1 and 43rd ± 2 meteorological weeks (MW), respectively. However, effective monsoon rainfall started at 24th MW (rainfall 92.7 mm, p > 56.7 % for 50 mm rainfall) and was terminated by the end of 40th MW (rainfall 90.7 mm, p < 59.6 % for 50 mm rainfall). During crop growth periods (seed to seed, 21st to 45th MW), the island received an average weekly rainfall of 65.1 ± 25.9 mm, while the corresponding weekly CWR was 47.8 ± 5.4 mm. Despite net water surplus of 353.9 mm during crop growth periods, there was a deficit of 159.5 mm water during MW of 18-23 (seedling raising) and MW of 41-45 (flowering to maturity stages). Water stress was observed in early lag vegetative stage of crop growth (32nd MW). The total dry spell frequency during panicle initiation and heading stage was computed as 40 of which 6 dry spells were >7 days in duration and reflected a significant ( p < 0.05) increasing trend (at 0.22 days year-1) over the years (1982-2010). The present study highlights the adaptive capacity of crop planning including abiotic stress

  18. Monsoon variability, crop water requirement, and crop planning for kharif rice in Sagar Island, India.

    PubMed

    Mandal, S; Choudhury, B U; Satpati, L N

    2015-12-01

    In the Sagar Island of Bay of Bengal, rainfed lowland rice is the major crop, grown solely depending on erratic distribution of southwest monsoon (SM) rainfall. Lack of information on SM rainfall variability and absence of crop scheduling accordingly results in frequent occurrence of intermittent water stress and occasional crop failure. In the present study, we analyzed long period (1982-2010) SM rainfall behavior (onset, withdrawal, rainfall and wetness indices, dry and wet spells), crop water requirement (CWR, by Food and Agriculture Organization (FAO) 56), and probability of weekly rainfall occurrence (by two-parameter gamma distribution) to assess the variability and impact on water availability, CWR, and rice productivity. Finally, crop planning was suggested to overcome monsoon uncertainties on water availability and rice productivity. Study revealed that the normal onset and withdrawal weeks for SM rainfall were 22nd ± 1 and 43rd ± 2 meteorological weeks (MW), respectively. However, effective monsoon rainfall started at 24th MW (rainfall 92.7 mm, p > 56.7 % for 50 mm rainfall) and was terminated by the end of 40th MW (rainfall 90.7 mm, p < 59.6 % for 50 mm rainfall). During crop growth periods (seed to seed, 21st to 45th MW), the island received an average weekly rainfall of 65.1 ± 25.9 mm, while the corresponding weekly CWR was 47.8 ± 5.4 mm. Despite net water surplus of 353.9 mm during crop growth periods, there was a deficit of 159.5 mm water during MW of 18-23 (seedling raising) and MW of 41-45 (flowering to maturity stages). Water stress was observed in early lag vegetative stage of crop growth (32nd MW). The total dry spell frequency during panicle initiation and heading stage was computed as 40 of which 6 dry spells were >7 days in duration and reflected a significant (p < 0.05) increasing trend (at 0.22 days year(-1)) over the years (1982-2010). The present study highlights the adaptive capacity of crop planning

  19. Chloroplast Genome Variation in Upland and Lowland Switchgrass

    PubMed Central

    Young, Hugh A.; Lanzatella, Christina L.; Sarath, Gautam; Tobias, Christian M.

    2011-01-01

    Switchgrass (Panicum virgatum L.) exists at multiple ploidies and two phenotypically distinct ecotypes. To facilitate interploidal comparisons and to understand the extent of sequence variation within existing breeding pools, two complete switchgrass chloroplast genomes were sequenced from individuals representative of the upland and lowland ecotypes. The results demonstrated a very high degree of conservation in gene content and order with other sequenced plastid genomes. The lowland ecotype reference sequence (Kanlow Lin1) was 139,677 base pairs while the upland sequence (Summer Lin2) was 139,619 base pairs. Alignments between the lowland reference sequence and short-read sequence data from existing sequence datasets identified as either upland or lowland confirmed known polymorphisms and indicated the presence of other differences. Insertions and deletions principally occurred near stretches of homopolymer simple sequence repeats in intergenic regions while most Single Nucleotide Polymorphisms (SNPs) occurred in intergenic regions and introns within the single copy portions of the genome. The polymorphism rate between upland and lowland switchgrass ecotypes was found to be similar to rates reported between chloroplast genomes of indica and japonica subspecies of rice which were believed to have diverged 0.2–0.4 million years ago. PMID:21887356

  20. Rain-fed fig yield as affected by rainfall distribution

    NASA Astrophysics Data System (ADS)

    Bagheri, Ensieh; Sepaskhah, Ali Reza

    2014-08-01

    Variable annual rainfall and its uneven distribution are the major uncontrolled inputs in rain-fed fig production and possibly the main cause of yield fluctuation in Istahban region of Fars Province, I.R. of Iran. This introduces a considerable risk in rain-fed fig production. The objective of this study was to find relationships between seasonal rainfall distribution and rain-fed fig production in Istahban region to determine the critical rainfall periods for rain-fed fig production and supplementary irrigation water application. Further, economic analysis for rain-fed fig production was considered in this region to control the risk of production. It is concluded that the monthly, seasonal and annual rainfall indices are able to show the effects of rainfall and its distribution on the rain-fed fig yield. Fig yield with frequent occurrence of 80 % is 374 kg ha-1. The internal rates of return for interest rate of 4, 8 and 12 % are 21, 58 and 146 %, respectively, that are economically feasible. It is concluded that the rainfall in spring especially in April and in December has negatively affected fig yield due to its interference with the life cycle of Blastophaga bees for pollination. Further, it is concluded that when the rainfall is limited, supplementary irrigation can be scheduled in March.

  1. Soil carbon sequestration in rainfed production systems in the semiarid tropics of India.

    PubMed

    Srinivasarao, Ch; Lal, Rattan; Kundu, Sumanta; Babu, M B B Prasad; Venkateswarlu, B; Singh, Anil Kumar

    2014-07-15

    Severe soil organic carbon (SOC) depletion is a major constraint in rainfed agroecosystems in India because it directly influences soil quality, crop productivity and sustainability. The magnitude of soil organic, inorganic and total carbon stocks in the semi-arid bioclimate is estimated at 2.9, 1.9 and 4.8 Pg respectively. Sorghum, finger millet, pearl millet, maize, rice, groundnut, soybean, cotton, food legumes etc. are predominant crop production systems with a little, if any, recycling of organic matter. Data from the long term experiments on major rainfed production systems in India show that higher amount of crop residue C input (Mg/ha/y) return back to soil in soybean-safflower (3.37) system practiced in Vertisol region of central India. Long term addition of chemical fertilizer and organic amendments improved the SOC stock. For every Mg/ha increase in SOC stock in the root zone, there occurs an increase in grain yield (kg/ha) of 13, 101, 90, 170, 145, 18 and 160 for groundnut, finger millet, sorghum, pearl millet, soybean and rice, respectively. Long-term cropping without using any organic amendment and/or mineral fertilizers can severely deplete the SOC stock which is the highest in groundnut-finger millet system (0.92 Mg C/ha/y) in Alfisols. Some agroforestry systems also have a huge potential of C sequestration to the extent of 10Mg/ha/y in short rotation eucalyptus and Leucaena plantations. The critical level of C input requirements for maintaining SOC at the antecedent level ranges from 1.1 to 3.5 Mg C/ha/y and differs among soil type and production systems. National level policy interventions needed to promote sustainable use of soil and water resources include prohibiting residue burning, reducing deforestation, promoting integrated farming systems and facilitating payments for ecosystem services. A wide spread adoption of these measures can improve soil quality through increase in SOC sequestration and improvement in agronomic productivity of

  2. Remote sensing based change analysis of rice environments in Odisha, India.

    PubMed

    Gumma, Murali Krishna; Mohanty, Samarendu; Nelson, Andrew; Arnel, Rala; Mohammed, Irshad A; Das, Satya Ranjan

    2015-01-15

    The rainfed rice-growing environment is perhaps one of the most vulnerable to water stress such as drought and floods. It is important to determine the spatial extent of the stress-prone areas to effectively and efficiently promote proper technologies (e.g., stress-tolerant varieties) to tackle the problem of sustainable food production. This study was conducted in Odisha state located in eastern India. Odisha is predominantly a rainfed rice ecosystem (71% rainfed and 29% canal irrigated during kharif-monsoon season), where rice is the major crop and staple food of the people. However, rice productivity in Odisha is one of the lowest in India and a significant decline (9%) in rice cultivated area was observed in 2002 (a drought year). The present study analyzed the temporal rice cropping pattern in various ecosystems and identified the stress-prone areas due to submergence (flooding) and water shortage. The spatial distribution of rice areas was mapped using MODIS (MOD09Q1) 250-m 8-day time-series data (2000-2010) and spectral matching techniques. The mapped rice areas were strongly correlated (R(2) = 90%) with district-level statistics. Also the class accuracy based on field-plot data was 84.8%. The area under the rainfed rice ecosystem continues to dominate, recording the largest share among rice classes across all the years. The use of remote-sensing techniques is rapid, cost-effective, and reliable to monitor changes in rice cultivated area over long periods of time and estimate the reduction in area cultivated due to abiotic stress such as water stress and submergence. Agricultural research institutes and line departments in the government can use these techniques for better planning, regular monitoring of land-use changes, and dissemination of appropriate technologies. Copyright © 2013 Elsevier Ltd. All rights reserved.

  3. Identification of Striga hermonthica-Resistant Upland Rice Varieties in Sudan and Their Resistance Phenotypes.

    PubMed

    Samejima, Hiroaki; Babiker, Abdel G; Mustafa, Ahmed; Sugimoto, Yukihiro

    2016-01-01

    Rice has become a major staple cereal in sub-Saharan Africa. Currently, upland rice cultivation is expanding particularly in rainfed areas where the root parasitic weed Striga hermonthica, a major constraint to cereal production, is endemic. Laboratory, pot, and semi-controlled open air experiments were performed to evaluate resistance of selected rice varieties in Sudan to a resident S. hermonthica population. In the laboratory, 27 varieties were screened for post-attachment resistance using the rhizotron technique. Varieties displaying high post-attachment resistance, Umgar, NERICA5, and NERICA13 together with NERICA4, NERICA18, and Nipponbare, a lowland rice variety, were further evaluated for performance and Striga resistance in pot and semi-controlled open air experiments and for germination inducing activity in a laboratory. In addition, comparative studies on reaction of Umgar, Kosti1 and Kosti2, released varieties for commercial production in Sudan, to the parasite were performed in two pot experiments. In the pot experiments Umgar and NERICA5, consistently, sustained the lowest Striga emergence (<2.2 Striga plants per pot), while NERICA13 and NERICA4 supported 1.8-5.7 and 8.7-16.4 Striga plants per pot, respectively. In an artificially Striga-infested field, number of emergent Striga plants per 10 rice hills, at harvest, was 2.0, 2.0, 4.8, 13.5, 13.3, and 18.3 on Umgar, NERICA5, NERICA13, NERICA4, NERICA18, and Nipponbare, respectively. Striga had no adverse effects on total above-ground parts and panicle dry weight in Umgar and NERICA5. Germination-inducing activity of root exudates, at 14 days after sowing onward, was markedly lower for Umgar than for NERICA5, NERICA13, NERICA4, and NERICA18. Based on these findings, Umgar has both pre and post-attachment resistance to a resident Striga population in Sudan. Kosti1 and Kosti2 did not exhibit Striga-resistance at the same level as Umgar. Further the resistance of NERICA5, a variety reported to be endowed

  4. Identification of Striga hermonthica-Resistant Upland Rice Varieties in Sudan and Their Resistance Phenotypes

    PubMed Central

    Samejima, Hiroaki; Babiker, Abdel G.; Mustafa, Ahmed; Sugimoto, Yukihiro

    2016-01-01

    Rice has become a major staple cereal in sub-Saharan Africa. Currently, upland rice cultivation is expanding particularly in rainfed areas where the root parasitic weed Striga hermonthica, a major constraint to cereal production, is endemic. Laboratory, pot, and semi-controlled open air experiments were performed to evaluate resistance of selected rice varieties in Sudan to a resident S. hermonthica population. In the laboratory, 27 varieties were screened for post-attachment resistance using the rhizotron technique. Varieties displaying high post-attachment resistance, Umgar, NERICA5, and NERICA13 together with NERICA4, NERICA18, and Nipponbare, a lowland rice variety, were further evaluated for performance and Striga resistance in pot and semi-controlled open air experiments and for germination inducing activity in a laboratory. In addition, comparative studies on reaction of Umgar, Kosti1 and Kosti2, released varieties for commercial production in Sudan, to the parasite were performed in two pot experiments. In the pot experiments Umgar and NERICA5, consistently, sustained the lowest Striga emergence (<2.2 Striga plants per pot), while NERICA13 and NERICA4 supported 1.8–5.7 and 8.7–16.4 Striga plants per pot, respectively. In an artificially Striga-infested field, number of emergent Striga plants per 10 rice hills, at harvest, was 2.0, 2.0, 4.8, 13.5, 13.3, and 18.3 on Umgar, NERICA5, NERICA13, NERICA4, NERICA18, and Nipponbare, respectively. Striga had no adverse effects on total above-ground parts and panicle dry weight in Umgar and NERICA5. Germination-inducing activity of root exudates, at 14 days after sowing onward, was markedly lower for Umgar than for NERICA5, NERICA13, NERICA4, and NERICA18. Based on these findings, Umgar has both pre and post-attachment resistance to a resident Striga population in Sudan. Kosti1 and Kosti2 did not exhibit Striga-resistance at the same level as Umgar. Further the resistance of NERICA5, a variety reported to be

  5. Genome-Wide Association Mapping of Root Traits in a Japonica Rice Panel

    PubMed Central

    Courtois, Brigitte; Audebert, Alain; Dardou, Audrey; Roques, Sandrine; Ghneim- Herrera, Thaura; Droc, Gaëtan; Frouin, Julien; Rouan, Lauriane; Gozé, Eric; Kilian, Andrzej; Ahmadi, Nourollah; Dingkuhn, Michael

    2013-01-01

    Rice is a crop prone to drought stress in upland and rainfed lowland ecosystems. A deep root system is recognized as the best drought avoidance mechanism. Genome-wide association mapping offers higher resolution for locating quantitative trait loci (QTLs) than QTL mapping in biparental populations. We performed an association mapping study for root traits using a panel of 167 japonica accessions, mostly of tropical origin. The panel was genotyped at an average density of one marker per 22.5 kb using genotyping by sequencing technology. The linkage disequilibrium in the panel was high (r2>0.6, on average, for 20 kb mean distances between markers). The plants were grown in transparent 50 cm × 20 cm × 2 cm Plexiglas nailboard sandwiches filled with 1.5 mm glass beads through which a nutrient solution was circulated. Root system architecture and biomass traits were measured in 30-day-old plants. The panel showed a moderate to high diversity in the various traits, particularly for deep (below 30 cm depth) root mass and the number of deep roots. Association analyses were conducted using a mixed model involving both population structure and kinship to control for false positives. Nineteen associations were significant at P<1e-05, and 78 were significant at P<1e-04. The greatest numbers of significant associations were detected for deep root mass and the number of deep roots, whereas no significant associations were found for total root biomass or deep root proportion. Because several QTLs for different traits were co-localized, 51 unique loci were detected; several co-localized with meta-QTLs for root traits, but none co-localized with rice genes known to be involved in root growth. Several likely candidate genes were found in close proximity to these loci. Additional work is necessary to assess whether these markers are relevant in other backgrounds and whether the genes identified are robust candidates. PMID:24223758

  6. Calibration of Daycent biogeochemical model for rice paddies in three agro-ecological zones in Peninsular India to optimize cropping practices and predict GHG emissions

    NASA Astrophysics Data System (ADS)

    Rajan, S.; Kritee, K.; Keough, C.; Parton, W. J.; Ogle, S. M.

    2014-12-01

    Rice is a staple for nearly half of the world population with irrigated and rainfed lowland rice accounting for about 80% of the worldwide harvested rice area. Increased atmospheric CO2 and rising temperatures are expected to adversely affect rice yields by the end of the 21st century. In addition, different crop management practices affect methane and nitrous oxide emissions from rice paddies antagonistically warranting a review of crop management practices such that farmers can adapt to the changing climate and also help mitigate climate change. The Daily DayCent is a biogeochemical model that operates on a daily time step, driven by four ecological drivers, i.e. climate, soil, vegetation, and management practices. The model is widely used to simulate daily fluxes of various gases, plant productivity, nutrient availability, and other ecosystem parameters in response to changes in land management and climate. We employed the DayCent model as a tool to optimize rice cropping practices in Peninsular India so as to develop a set of farming recommendations to ensure a triple win (i.e. higher yield, higher profit and lower GHG emissions). We applied the model to simulate both N2O and CH4 emissions, and crop yields from four rice paddies in three different agro-ecological zones under different management practices, and compared them with measured GHG and yield data from these plots. We found that, like all process based models, the biggest constraint in using the model was input data acquisition. Lack of accurate documentation of historic land use and management practices, missing historical daily weather data, and difficulty in obtaining digital records of soil and crop/vegetation parameters related to our experimental plots came in the way of our execution of this model. We will discuss utilization of estimates based on available literature, or knowledge-based values in lieu of missing measured parameters in our simulations with DayCent which could prove to be a

  7. Natural leaf senescence: probed by chlorophyll fluorescence, CO2 photosynthetic rate and antioxidant enzyme activities during grain filling in different rice cultivars.

    PubMed

    Panda, Debabrata; Sarkar, Ramani Kumar

    2013-01-01

    Natural leaf senescence was investigated in four rainfed lowland rice cultivars, FR 13A (tolerant to submergence), Sabita and Sarala (adapted to medium depth, 0-50 cm stagnant flooding) and Dengi (conventional farmers' cultivar). Changes in the levels of pigment content, CO2 photosynthetic rate, photosystem II photochemistry and anti-oxidant enzyme activities of flag leaves during grain-filling stage were investigated. Chlorophyll content, photochemical efficiency of photosystem II and CO2 photosynthetic rate decreased significantly with the progress of grain-filling. Likely, the activities of antioxidant enzymes namely, superoxide dismutase, catalase, guaiacol peroxidase and ascorbate peroxidase decreased with progress of grain-filling. A substantial difference was observed among the four cultivars for the sustainability index (SI) of different photosynthetic parameters and antioxidant enzyme activities; SIs of those parameters, in general, were lower in low yielding cultivar FR 13A compared to the other three cultivars. Among the four cultivars Sabita gave maximum grain yield. Yet, SI of Pn was greater in Sarala and Dengi compared to the Sabita. SIs of electron transport (ETo/CS), maximal photochemical efficiency (Fv/Fm), area above Fo and Fm, catalase and ascorbate peroxidase were also greater in Sarala and Dengi. The data showed that among the different Chl a fluorescence parameters, PI could be used with greater accuracy to distinguish slow and fast senescence rice cultivars during grain-filling period. It was concluded that maintaining the vitality of rice plants during grain-filling gave guarantee to synthesize carbohydrate, however greater yield could be realized provided superior yield attributing parameters are present.

  8. Postcolonial Hybrids in "The Lowland"

    ERIC Educational Resources Information Center

    Ghoreishi, Seyedeh Zahra; Bordbari, Zahra

    2016-01-01

    This paper delves into Jhumpa Lahiri's 2013 novel, "The Lowland", to analyze the diasporic experience of the Indianborn characters. Homi Bhabha's postcolonial approach is utilized to demonstrate the ways in which the characters perceive the immigration experience, and to unravel the causes of their despair, the disintegration of their…

  9. Blackbirds and the southern rice crop

    USGS Publications Warehouse

    Meanley, Brooke

    1971-01-01

    In the 1700's and 1800's, rice was grown in the lowlands of South Carolina, Georgia, and North Carolina - on the major migratory route of the bobolink (Dolichonyx oryzivorus), the historic "ricebird" of that area because of its consumption of ripening rice. By the late 1800's the rice-growing industry had largely shifted to the coastal prairies of Louisiana and Texas, which are bordered by some 5 million acres of marshland-breeding habitat for the redwinged blackbird (Agelaius phoeniceus) and the boat-tailed grackle (Cassidix mexicanus). By 1900, rice was being grown on the Grand Prairie of eastern Arkansas, which bestrides the largest blackbird flyway in the country. In recent decades, rice culture has spread to other sections of Arkansas and thence to contiguous areas in Louisiana, Mississippi, Tennesee, and Missouri. In effect, then, man has taken the rice to the blackbirds.

  10. The role of aquaporin RWC3 in drought avoidance in rice.

    PubMed

    Lian, Hong-Li; Yu, Xin; Ye, Qin; Ding, Xiaodong; Kitagawa, Yoshichika; Kwak, Sang-Soo; Su, Wei-Ai; Tang, Zhang-Cheng; Ding, Xiao-Song

    2004-04-01

    Although the discovery of aquaporins in plants has resulted in a paradigm shift in the understanding of plant water relations, the relationship between aquaporins and drought resistance still remains elusive. From an agronomic viewpoint, upland rice is traditionally considered as showing drought avoidance. In the investigation of different morphological and physiological responses of upland rice (Oryza sativa L. spp indica cv. Zhonghan 3) and lowland rice (O. sativa L. spp japonica cv. Xiushui 63) to water deficit, we observed young leaf rolling and the remarkable decline of cumulative transpiration in the upland rice. The expression of water channel protein RWC3 mRNA was increased in upland rice at the early response (up to 4 h) to the 20% polyethylene glycol (PEG) 6000 treatment, whereas there was no significant expression changes in lowland rice. Protein levels were increased in upland rice and decreased in lowland rice at 10 h after the water deficit. The up-regulation of RWC3 in upland rice fits well with the knowledge that upland rice adopts the mechanism of drought avoidance. The physiological significance of this RWC3 up-regulation was then explored with the over-expression of RWC3 in transgenic lowland rice (O. sativa L. spp japonica cv. Zhonghua 11) controlled by a stress-inducible SWPA2 promoter. Compared to the wild-type plant, the transgenic lowland rice exhibited higher root osmotic hydraulic conductivity (Lp), leaf water potential and relative cumulative transpiration at the end of 10 h PEG treatment. These results indicated that RWC3 probably played a role in drought avoidance in rice.

  11. Effect of nitrogen application rate on yield and quality in irrigated and rainfed cotton

    USDA-ARS?s Scientific Manuscript database

    Studies on the effect of nitrogen (N) application rates on lint yield and fiber quality in irrigated and rainfed cotton were conducted for two years in a humid climate. In 2013, cotton was planted in 48 plots. 24 plots were irrigated and the other 24 pots were rainfed. Six N application rates (0, 39...

  12. How can varieties and rain-fed production environments affect malting quality in spring barley?

    USDA-ARS?s Scientific Manuscript database

    Rain-fed barley production environments can be highly variable across a region and across years. Almost all malting barley production in Washington State is under rain-fed conditions. The industry has noticed that in some cases malt beta-glucan levels and other malting quality parameters have been u...

  13. Climate change impacts on global rainfed agricultural land availability

    NASA Astrophysics Data System (ADS)

    Zhang, X.; Cai, X.

    2010-12-01

    Global rainfed agricultural land availability can be subject to significant changes in both magnitude and spatial distribution due to climate change. We assess the possible changes using current and projected climate data from thirteen general circulation models (GCMs) under two emission scenarios, A1B & B1, together with global databases on land, including soil properties and slope. Two ensemble methods with the set of GCMs, Simple Average Method (SAM) and Root Mean Square Error Ensemble Method (RMSEMM), are employed to abate uncertainty involved in global GCM projections for assembling regional climate. Fuzzy logic, which handles land classification in an approximate yet efficient way, is adopted to estimate the land suitability through empirically determined membership functions and fuzzy rules chosen through a learning process based on remote sensed crop land products. Land suitability under five scenarios, which include the present-climate baseline scenario and four projected scenarios, A1B-SAM, A1B-RMSEMM, B1-SAM, and B1-RMSEMM, are assessed for both global and seven important agricultural regions in the world, Africa, China, India, Europe (excluding Russia), Russia, South America, and U.S. It is found that countries at the high latitudes of north hemisphere are more likely to benefit from climate change with respect to agricultural land availability; while countries at mid- and low latitudes may suffer different levels of loss of potential arable land. Expansions of the gross potential arable land are likely to occur in regions at the north high latitudes, including Russia, North China and U.S., while land shrinking can be expected in South America, Africa, India and Europe. Although the greatest potential for agricultural expansion lies in Africa and South America, with current cultivated land accounting for 20% and 13% respectively of the net potential arable land, negative effects from climate change may decline the potential. In summary, climate change

  14. From Water Dynamics to Rainfed Landscapes with GRASS GIS

    NASA Astrophysics Data System (ADS)

    Chemin, Yann; van Brakel, Martin; Johnston, Robyn; Curnow, Jayne

    2014-05-01

    Variability in water availability is a key determinant of risk and constraint to productivity in rainfed agricultural systems. Understanding the dynamics of water availability across both spatial and temporal scales is essential to managing water and optimize production. This research proposes to look at both the physical measurement of water availability and water user perceptions of landscapes and water availability. Evapotranspiration makes up about three quarters of the transiting water in a landscape, it is composed of evaporation (water bodies, soil) and transpiration, the vegetation biomass growing quantity. This work will develop a methodology for defining landscapes based on water dynamics to be used at the interface of WLE research. The GRASS GIS Imagery, Landscape and Temporal toolkits form the basis of the methodological development, from evapotranspiration modeling and landscape analysis to spatio-temporal analysis.

  15. Stabilized nitrogen fertilizers and application rate influence nitrogen losses under rainfed spring wheat

    USDA-ARS?s Scientific Manuscript database

    Nitrogen (N) losses associated with fertilizer application have negative economic and environmental consequences, but urease and nitrification inhibitors have potential to reduce N losses. The effectiveness of these inhibitors has been studied extensively in irrigated but not rainfed systems. Theref...

  16. Abandoned Rice Fields Make Streams Go Dry in Upland Landscapes

    NASA Astrophysics Data System (ADS)

    Jayawickreme, D.

    2015-12-01

    In South Asia, new economic realities are driving many rural rice farmers out of agriculture. With increasing neglect, abandonment, and rising conversions of centuries old rice fields into other uses, ecological and environmental consequences of these transitions are becoming progressively clear. Field observations in Sri Lanka's central highlands suggest that small shifts in rice to non-rice land uses in headwater watersheds can have a domino effect on the productivity and viability of rice fields and other ecological systems downstream by inflicting groundwater recharge reductions, lowering groundwater yields, and causing other hydrological changes. Preliminary analysis shows that although rice itself is a very water intensive crop, the presence of rain-fed upland rice-fields is hugely beneficial to the watersheds they reside. In particular, water benefits of rice appear to be derived from ponded conditions (3-5 inches of standing water) in which rice is grown, and the contribution rice fields makes to enhance water retention and storage capacity of their watersheds during the monsoon season that coincide with the cropping season. In the absence of well managed rice-fields, hilly upland landscapes produce more runoff and retain little rainwater during the wet season. Furthermore, after centuries of intensive use, much of South Asia's rice fields are nutrient poor and minimally productive without fertilizer applications and other interventions. Consequently, when abandoned, soil erosion and other impacts that affect aquatic ecosystems and watershed health also emerge. Despite these multiple concerns however, little research is currently done to better understand the environmental significance of rice cultivations that are a dominant land-use in many South Asian landscapes. The aim of this presentation is to stir interest among the scientific community to engage more broadly in rice, water, and environmental change research in the face of new economic realities in

  17. Future soil moisture and temperature extremes imply expanding suitability for rainfed agriculture in temperate drylands.

    PubMed

    Bradford, John B; Schlaepfer, Daniel R; Lauenroth, William K; Yackulic, Charles B; Duniway, Michael; Hall, Sonia; Jia, Gensuo; Jamiyansharav, Khishigbayar; Munson, Seth M; Wilson, Scott D; Tietjen, Britta

    2017-10-10

    The distribution of rainfed agriculture, which accounts for approximately ¾ of global croplands, is expected to respond to climate change and human population growth and these responses may be especially pronounced in water limited areas. Because the environmental conditions that support rainfed agriculture are determined by climate, weather, and soil conditions that affect overall and transient water availability, predicting this response has proven difficult, especially in temperate regions that support much of the world's agriculture. Here, we show that suitability to support rainfed agriculture in temperate dryland climates can be effectively represented by just two daily environmental variables: moist soils with warm conditions increase suitability while extreme high temperatures decrease suitability. 21(st) century projections based on daily ecohydrological modeling of downscaled climate forecasts indicate overall increases in the area suitable for rainfed agriculture in temperate dryland regions, especially at high latitudes. The regional exception to this trend was Europe, where suitability in temperate dryland portions will decline substantially. These results clarify how rising temperatures interact with other key drivers of moisture availability to determine the sustainability of rainfed agriculture and help policymakers, resource managers, and the agriculture industry anticipate shifts in areas suitable for rainfed cultivation.

  18. Physiological mechanisms contributing to the QTL-combination effects on improved performance of IR64 rice NILs under drought

    PubMed Central

    Henry, Amelia; Swamy, B. P. Mallikarjuna; Dixit, Shalabh; Torres, Rolando D.; Batoto, Tristram C.; Manalili, Mervin; Anantha, M. S.; Mandal, N. P.; Kumar, Arvind

    2015-01-01

    Characterizing the physiological mechanisms behind major-effect drought-yield quantitative trait loci (QTLs) can provide an understanding of the function of the QTLs—as well as plant responses to drought in general. In this study, we characterized rice (Oryza sativa L.) genotypes with QTLs derived from drought-tolerant traditional variety AdaySel that were introgressed into drought-susceptible high-yielding variety IR64, one of the most popular megavarieties in South Asian rainfed lowland systems. Of the different combinations of the four QTLs evaluated, genotypes with two QTLs (qDTY 2.2 + qDTY 4.1) showed the greatest degree of improvement under drought compared with IR64 in terms of yield, canopy temperature, and normalized difference vegetation index (NDVI). Furthermore, qDTY 2.2 and qDTY 4.1 showed a potential for complementarity in that they were each most effective under different severities of drought stress. Multiple drought-response mechanisms were observed to be conferred in the genotypes with the two-QTL combination: higher root hydraulic conductivity and in some cases greater root growth at depth. As evidenced by multiple leaf water status and plant growth indicators, these traits affected transpiration but not transpiration efficiency or harvest index. The results from this study highlight the complex interactions among major-effect drought-yield QTLs and the drought-response traits they confer, and the need to evaluate the optimal combinations of QTLs that complement each other when present in a common genetic background. PMID:25680791

  19. The water budget of rainfed maize and bean intercrop

    NASA Astrophysics Data System (ADS)

    Walker, S.; Ogindo, H. O.

    Food production in the South African Development Community (SADC) region is predominantly under rainfed conditions and therefore experiences annual fluctuations due to the rainfall variability. Although the staple food of maize ( Zea mays) is commonly grown in the same field as dry beans ( Phaseolus vulgaris) little work has been done to characterize the soil water budget of this intercropping system. The evapotranspiration can theoretically be divided into transpiration from the leaves and evaporation from the soil surface. However, it is difficult to separate the components in field studies. In this paper the Ritchie model is used to estimate the soil surface evaporation using the fractional radiation interception which depends on the crop leaf area. The intercropping system has higher leaf area than the sole crops of both maize and beans in all seasons. Therefore, the soil surface is shaded and the canopy is more dense resulting in a lower soil surface evaporation. The water budget thus gives a higher value of transpiration for the intercrop during each of the four growing seasons. This appears to be due to the complimentary use of the water resources by the maize and bean plants in the intercropping system. This illustrates the ability of the intercrop to use the available soil water in a semi-arid environment more productively. Thus the experience of the small-holder farmers in the SADC region is based on sound physical principles of water use by the two crops.

  20. Simulated yield potential by irrigation and yield gap of rainfed soybean using APEX model in a humid region

    USDA-ARS?s Scientific Manuscript database

    Globally, soybean is typically grown under rainfed conditions. In order to determine how much maximum yield could be increased by irrigation, it is crucial to investigate the yield potential (Yp) under water unstressed condition and yield gap (Yg, between Yp and rainfed yield (Yw)). It is also impo...

  1. Simulating soybean productivity under rainfed conditions for major soil types using APEX model in East Central Mississippi

    Treesearch

    Bangbang Zhang; Gary Feng; John J. Read; Xiangbin Kong; Ying Ouyang; Ardeshir Adeli; Johnie N. Jenkins

    2016-01-01

    Knowledge of soybean yield constraints under rainfed conditions on major soil types in East CentralMississippi would assist growers in the region to effectively utilize the benefits of water/irrigation man-agement. The objectives of this study were to use the Agricultural Policy/Environmental eXtender (APEX)agro-ecosystem model to simulate rainfed soybean grain yield (...

  2. Simulating soybean productivity under rainfed conditions for major soil types using APEX model in East Central Mississippi

    USDA-ARS?s Scientific Manuscript database

    Because soybean is commonly grown under rainfed conditions in Mississippi, and farmers recognize benefits of installing irrigation, knowledge of rainfed soybean productivity and yield difference of different soil types is needed for deciding where irrigation may be most effective. This research empl...

  3. Variation in tolerance of rice to long-term stagnant flooding that submerges most of the shoot will aid in breeding tolerant cultivars

    PubMed Central

    Vergara, Georgina V.; Nugraha, Yudhistira; Esguerra, Manuel Q.; Mackill, David J.; Ismail, Abdelbagi M.

    2014-01-01

    Stagnant flooding (SF) is a major problem in rainfed lowlands where floodwater of 25–50 cm stagnates in the field for most of the season. We aimed to establish a system for phenotyping SF tolerance and identifying tolerant germplasm through screening of landraces. A total of 626 rice accessions were evaluated over 3 years under control conditions and two levels of SF. Floodwater was raised to 20 cm at 25 or 30 days after transplanting (DAT). In one trial, the depth was increased subsequently by 5 cm a week and in another (severe stress), it was increased to 40 cm at 37 DAT and to 50 cm at 42 DAT. In both trials, water depth was maintained at 50–60 cm until maturity. In all cases, no plant was completely submerged. Plant height, elongation rate and yield were measured at maturity. Genotypes best suited to SF showed moderate elongation of 1.3–2.3 cm day−1 under SF. In contrast, semi-dwarf and fast-elongating types performed poorly. Subsequent trials using 18 genotypes, including six pairs of near isogenic lines (NILs) with or without SUB1 showed that all SUB1 NILs were sensitive to SF. Five of the other six genotypes contained SUB1 and were SF tolerant, suggesting the possibility of combining tolerances to complete submergence (SUB1) and SF. Stem starch and soluble sugar concentrations were similar under control conditions among the 18 genotypes, but starch was depleted by 37 % under SF, with less depletion in tolerant genotypes. SUB1 NILs contained similar concentrations of starch and sugars under SF. We conclude that survival and yield under SF are dependent on moderate elongation, high tillering, lesser carbohydrate depletion and higher fertility. The tolerant genotypes identified here performed strongly in both wet and dry seasons and will be used to identify tolerance mechanisms and alleles for use in marker-assisted breeding. PMID:25202124

  4. Soil management and green water in sloping rainfed vineyards

    NASA Astrophysics Data System (ADS)

    José Marqués Pérez, María; Ruíz-Colmenero, Marta; García-Díaz, Andrés; Bienes Allas, Ramón

    2017-04-01

    Improved crop production in areas with restricted water availability is of particular interest. Farmers need to maximize the water use efficiency when the possibilities of further extension of irrigation are limited and water is becoming scarce and expensive. Water in rainfed crops depends on rainfall depth and soil characteristics such as texture and structure, water holding capacity, previous moisture, infiltration, soil surface conditions, steepness and slope length. Land management practices can be used to maximise water availability. In previous studies the unwillingness of farmers to change their practices towards more sustainable use was mainly due to the worry about water competition. This work is aimed at understanding the influence of management practices in the water partitioning of this land use. This study was conducted in a sloping vineyard in the centre of Spain. A rain gauge recorded rainfall depth and intensity in the area. Three different soil management practices were considered: 1) traditional tillage, 2) permanent cover and 3) mowed cover of cereals, both sown in the strips between vines. Two moisture sensors were buried at 10 and 35 cm depths. Three replicates per management practice were performed. It is expected that the lack of tillage increase the potential for litter to protect the soil surface against raindrop impact and to contribute to increasing soil organic carbon, and the corresponding increase in infiltration and water holding capacity. The analysis of two years of daily records of rainfall, runoff and soil moisture are intended to establish any influence of management practices on the partitioning of water. Particularly, the so-called "green water" was estimated, i.e. the fraction of rainfall that infiltrates into the soil and will be further available to plants. Soil characteristics such as texture, structure, moisture, infiltration were established. In addition simulated rainfalls carried out in summer and winter over bounded

  5. Methane Emissions From Global Paddy Rice Agriculture - a New Estimate Based on DNDC Model Simulations

    NASA Astrophysics Data System (ADS)

    Hagen, S. C.; Li, C.; Salas, W.; Ingraham, P.; Li, J.; Beach, R.; Frolking, S.

    2012-12-01

    Roughly one-quarter of global methane emissions to the atmosphere come from the agricultural sector. Agricultural emissions are dominated by livestock (ruminants) and paddy-rice agriculture. We report on a new estimate of global methane emissions from paddy rice c.2010, based on DNDC model simulations of rice cropping around the world. We first generated a global map of rice cropping at 0.5°-resolution, based on existing global crop maps and various other published data. For each 0.5° grid cell that has rice agriculture, we simulated all rice cropping systems that our mapping indicated to be occurring there - irrigated and/or rainfed; single-rice, double-rice, triple-rice, and/or rice-rotated with other upland crops - under local climate and soil conditions, with assumptions about crop management (e.g., fertilizer type and amount, irrigation, flooding frequency and duration, manure application, tillage, crop residue management). We estimate global paddy rice emissions at 23 Tg CH4/yr from 120 Mha of rice paddies (land area) and 160 Mha of rice cropping (harvested area) for the baseline management scenario. We also report on the spatial distribution of these emissions, and the impacts of various management alternatives (flooding methods, fertilizer types, crop residue incorporation etc.) on yield, soil carbon sequestration and emissions of methane and nitrous oxide. For example, simulations with continuous flooding on all paddies increased simulated global paddy rice emissions to 33 Tg CH4/yr, while simulations where all fertilizer was applied as ammonium sulfate reduced simulated global paddy rice emissions to about 19 Tg CH4/yr. Simulated global paddy rice yield was about 320 Tg C in grain.

  6. Nitrous oxide emissions with enhanced efficiency nitrogen fertilizers in rainfed system

    USDA-ARS?s Scientific Manuscript database

    The use of enhanced efficiency nitrogen (N) fertilizers can increase crop N utilization and lead to lower emissions of the greenhouse gas nitrous oxide (N2O). To determine potential benefit of four enhanced efficiency fertilizers with rain-fed corn production in central Pennsylvania, USA, N2O emissi...

  7. The archaeobotany of Asian rice expansion and the development of wet-field cultivation

    NASA Astrophysics Data System (ADS)

    Fuller, D.

    2008-12-01

    Archaeobotanical evidence provides direct data on past human diet and agriculture, including a geographical and chronological framework for studying the expansion of rice agriculture. The growth of systematic archaeobotanical sampling in recent years has allowed for the past presence of rice to be seen in relation to cultivation of other crops and associated weeds. The weed flora provides a basis for inferring the nature of cultivation systems, whether rain-fed dry rice or wetland "paddy" rice, a key distinction for considerations of past methane production. Nevertheless, current data is very unevenly distributed. This poster will summarize available evidence for the origins and spread of rice in South Asia (India and Pakistan), and mainland and Island Southeast Asia deriving from an earlier Chinese domestication. Where possible, such as in India or China, the potential of the weed flora remains for distinguishing wetland rice crops will be summarized. In broad terms, although the origins of rice use and cultivation begins by or during the Middle Holocene (6000- 3000 BC), rice cultivation spread outside the regions of the wild progenitor after this time. Two phases of rice expansion can be distinguished. Phase 1, between 3000 and 1500 BC, introduced rice to Southeast Asia, probably under wetland cultivation, and the spread of dry rice over northern India and Pakistan. Phase 2, taking place between 1000 and 0 BC, sees the spread of rice throughout the Southern Indian Peninsula, with weed evidence suggesting irrigated wetland rice. Similarly, this period sees the spread of intensive paddy agriculture through Korea and Japan, but in Southeast Asia is probably related to a spread of rice in upland, dry field systems.

  8. Fine mapping QTL for drought resistance traits in rice (Oryza sativa L.) using bulk segregant analysis.

    PubMed

    Salunkhe, Arvindkumar Shivaji; Poornima, R; Prince, K Silvas Jebakumar; Kanagaraj, P; Sheeba, J Annie; Amudha, K; Suji, K K; Senthil, A; Babu, R Chandra

    2011-09-01

    Drought stress is a major limitation to rice (Oryza sativa L.) yields and its stability, especially in rainfed conditions. Developing rice cultivars with inherent capacity to withstand drought stress would improve rainfed rice production. Mapping quantitative trait loci (QTLs) linked to drought resistance traits will help to develop rice cultivars suitable for water-limited environments through molecular marker-assisted selection (MAS) strategy. However, QTL mapping is usually carried out by genotyping large number of progenies, which is labour-intensive, time-consuming and cost-ineffective. Bulk segregant analysis (BSA) serves as an affordable strategy for mapping large effect QTLs by genotyping only the extreme phenotypes instead of the entire mapping population. We have previously mapped a QTL linked to leaf rolling and leaf drying in recombinant inbred (RI) lines derived from two locally adapted indica rice ecotypes viz., IR20/Nootripathu using BSA. Fine mapping the QTL will facilitate its application in MAS. BSA was done by bulking DNA of 10 drought-resistant and 12 drought-sensitive RI lines. Out of 343 rice microsatellites markers genotyped, RM8085 co-segregated among the RI lines constituting the respective bulks. RM8085 was mapped in the middle of the QTL region on chromosome 1 previously identified in these RI lines thus reducing the QTL interval from 7.9 to 3.8 cM. Further, the study showed that the region, RM212-RM302-RM8085-RM3825 on chromosome 1, harbours large effect QTLs for drought-resistance traits across several genetic backgrounds in rice. Thus, the QTL may be useful for drought resistance improvement in rice through MAS and map-based cloning.

  9. Linkage Mapping of Stem Saccharification Digestibility in Rice

    PubMed Central

    Hua, Cangmei; Sun, Lili; Ali, Imran; Huang, Linli; Yu, Chunyan; Simister, Rachael; Steele-King, Clare; Gan, Yinbo; McQueen-Mason, Simon J.

    2016-01-01

    Rice is the staple food of almost half of the world population, and in excess 90% of it is grown and consumed in Asia, but the disposal of rice straw poses a problem for farmers, who often burn it in the fields, causing health and environmental problems. However, with increased focus on the development of sustainable biofuel production, rice straw has been recognized as a potential feedstock for non-food derived biofuel production. Currently, the commercial realization of rice as a biofuel feedstock is constrained by the high cost of industrial saccharification processes needed to release sugar for fermentation. This study is focused on the alteration of lignin content, and cell wall chemotypes and structures, and their effects on the saccharification potential of rice lignocellulosic biomass. A recombinant inbred lines (RILs) population derived from a cross between the lowland rice variety IR1552 and the upland rice variety Azucena with 271 molecular markers for quantitative trait SNP (QTS) analyses was used. After association analysis of 271 markers for saccharification potential, 1 locus and 4 pairs of epistatic loci were found to contribute to the enzymatic digestibility phenotype, and an inverse relationship between reducing sugar and lignin content in these recombinant inbred lines was identified. As a result of QTS analyses, several cell-wall associated candidate genes are proposed that may be useful for marker-assisted breeding and may aid breeders to produce potential high saccharification rice varieties. PMID:27415441

  10. Groundwater flood hazards in lowland karst terrains

    NASA Astrophysics Data System (ADS)

    Naughton, Owen; McCormack, Ted

    2016-04-01

    The spatial and temporal complexity of flooding in karst terrains pose unique flood risk management challenges. Lowland karst landscapes can be particularly susceptible to groundwater flooding due to a combination of limited drainage capacity, shallow depth to groundwater and a high level of groundwater-surface water interactions. Historically the worst groundwater flooding to have occurred in the Rep. of Ireland has been centred on the Gort Lowlands, a karst catchment on the western coast of Ireland. Numerous notable flood events have been recorded throughout the 20th century, but flooding during the winters of 2009 and 2015 were the most severe on record, inundating an area in excess of 20km2 and causing widespread and prolonged disruption and damage to property and infrastructure. Effective flood risk management requires an understanding of the recharge, storage and transport mechanisms during flood conditions, but is often hampered by a lack of adequate data. Using information gathered from the 2009 and 2015 events, the main hydrological and geomorphological factors which influence flooding in this complex lowland karst groundwater system under are elucidated. Observed flood mechanisms included backwater flooding of sinks, overland flow caused by the overtopping of sink depressions, high water levels in turlough basins, and surface ponding in local epikarst watersheds. While targeted small-scale flood measures can locally reduce the flood risk associated with some mechanisms, they also have the potential to exacerbate flooding down-catchment and must be assessed in the context of overall catchment hydrology. This study addresses the need to improve our understanding of groundwater flooding in karst terrains, in order to ensure efficient flood prevention and mitigation in future and thus help achieve the aims of the EU Floods Directive.

  11. Development of a coupled model of a distributed hydrological model and a rice growth model for optimizing irrigation schedule

    NASA Astrophysics Data System (ADS)

    Tsujimoto, Kumiko; Homma, Koki; Koike, Toshio; Ohta, Tetsu

    2013-04-01

    A coupled model of a distributed hydrological model and a rice growth model was developed in this study. The distributed hydrological model used in this study is the Water and Energy Budget-based Distributed Hydrological Model (WEB-DHM) developed by Wang et al. (2009). This model includes a modified SiB2 (Simple Biosphere Model, Sellers et al., 1996) and the Geomorphology-Based Hydrological Model (GBHM) and thus it can physically calculate both water and energy fluxes. The rice growth model used in this study is the Simulation Model for Rice-Weather relations (SIMRIW) - rainfed developed by Homma et al. (2009). This is an updated version of the original SIMRIW (Horie et al., 1987) and can calculate rice growth by considering the yield reduction due to water stress. The purpose of the coupling is the integration of hydrology and crop science to develop a tool to support decision making 1) for determining the necessary agricultural water resources and 2) for allocating limited water resources to various sectors. The efficient water use and optimal water allocation in the agricultural sector are necessary to balance supply and demand of limited water resources. In addition, variations in available soil moisture are the main reasons of variations in rice yield. In our model, soil moisture and the Leaf Area Index (LAI) are calculated inside SIMRIW-rainfed so that these variables can be simulated dynamically and more precisely based on the rice than the more general calculations is the original WEB-DHM. At the same time by coupling SIMRIW-rainfed with WEB-DHM, lateral flow of soil water, increases in soil moisture and reduction of river discharge due to the irrigation, and its effects on the rice growth can be calculated. Agricultural information such as planting date, rice cultivar, fertilization amount are given in a fully distributed manner. The coupled model was validated using LAI and soil moisture in a small basin in western Cambodia (Sangker River Basin). This

  12. Hyperspectral prediction of leaf area index of winter wheat in irrigated and rainfed fields.

    PubMed

    Li, Guangxin; Wang, Chao; Feng, Meichen; Yang, Wude; Li, Fangzhou; Feng, Ruiyun

    2017-01-01

    The growth status of winter wheat in irrigated field and rainfed field are obviously different and the field types may have an effect on the predictive accuracy of hyperspectral model. The objectives of the present study were to understand the difference of spectral sensitive wavelengths for leaf area index (LAI) in two field types and realize its hyperspectral prediction. In study, a total of 31 and 28 sample sites in irrigated fields and rainfed fields respectively were selected from Wenxi County, and the LAI and canopy spectra were also collected at the main grow stage of winter wheat. The method of successive projections algorithm (SPA) was applied by selecting the important wavelengths, and the multiple linear regression (MLR) and partial least squares regression (PLSR) were used to construct the predictive model based on the important wavelengths and full wavelengths, respectively. Moreover, the parameters of variable importance project (VIP) and B-coefficient derived from PLSR analysis were implemented to validate the evaluated wavelengths using the SPA method. The sensitive wavelengths of LAI for irrigated field and rainfed field were 404, 407, 413, 417, 450, 677, 715, 735, 816, 1127 and 404, 406, 432, 501, 540, 679, 727, 779, 1120, 1290 nm, respectively, and these wavelengths proved to be highly correlated with LAI. Compared with the model performance based on the SPA-MLR and PLSR methods, the method of SPA-MLR was proved to be better (rainfed field: R2 = 0.736, RMSE = 1.169, RPD = 1.6245; irrigated field: R2 = 0.716, RMSE = 1.059, RPD = 1.538). Moreover, the predictive model of LAI in rainfed fields had a better accuracy than the model in irrigated fields. The results from this study indicated that it was necessary to classify the field type while monitoring the winter wheat using the remote sensing technology. This study also demonstrated that the multivariate method of SPA-MLR could accurately evaluate the sensitive wavelengths and construct the

  13. Genomic prediction for winter survival in lowland switchgrass

    USDA-ARS?s Scientific Manuscript database

    Switchgrass (Panicum virgatum L.) is a North American native perennial warm season grass and a promising cellulosic bioenergy feedstock. It has two ecotypes – lowland and upland. The lowland ecotype has generated considerable interest because of its higher biomass compared to the upland ecotype. How...

  14. Sources, distribution and export coefficient of phosphorus in lowland polders of Lake Taihu Basin, China.

    PubMed

    Huang, Jiacong; Gao, Junfeng; Jiang, Yong; Yin, Hongbin; Amiri, Bahman Jabbarian

    2017-09-21

    Identifying phosphorus (P) sources, distribution and export from lowland polders is important for P pollution management, however, is challenging due to the high complexity of hydrological and P transport processes in lowland areas. In this study, the spatial pattern and temporal dynamics of P export coefficient (PEC) from all the 2539 polders in Lake Taihu Basin, China were estimated using a coupled P model for describing P dynamics in a polder system. The estimated amount of P export from polders in Lake Taihu Basin during 2013 was 1916.2 t/yr, with a spatially-averaged PEC of 1.8 kg/ha/yr. PEC had peak values (more than 4.0 kg/ha/yr) in the polders near/within the large cities, and was high during the rice-cropping season. Sensitivity analysis based on the coupled P model revealed that the sensitive factors controlling the PEC varied spatially and changed through time. Precipitation and air temperature were the most sensitive factors controlling PEC. Culvert controlling and fertilization were sensitive factors controlling PEC during some periods. This study demonstrated an estimation of PEC from 2539 polders in Lake Taihu Basin, and an identification of sensitive environmental factors affecting PEC. The investigation of polder P export in a watershed scale is helpful for water managers to learn the distribution of P sources, to identify key P sources, and thus to achieve best management practice in controlling P export from lowland areas. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Interior River Lowland Ecoregion Summary Report

    USGS Publications Warehouse

    Karstensen, Krista A.

    2008-01-01

    ECOREGION DESCRIPTION The Interior River Lowlands ecoregion encompasses 93,200 square kilometers (km2) across southern and western Illinois, southwest Indiana, east-central Missouri, and fractions of northwest Kentucky and southeast Iowa. The ecoregion includes the confluence areas of the Mississippi, Missouri, Ohio, Illinois, and Wabash Rivers, and their tributaries. This ecoregion was formed in non-resident, non-calcareous sedimentary rock (U.S. Environmental Protection Agency, 2006). The unstratified soil deposits present north of the White River in Indiana are evidence that pre-Wisconsinan ice once covered much of the Interior River Lowlands. The geomorphic characteristics of this area also include terraced valleys filled with alluvium as well as outwash, acolian, and lacustrine deposits. Historically, agricultural land use has been a vital economic resource for this region. The drained alluvial soils are farmed for feed grains and soybeans, whereas the valley uplands also are used for forage crops, pasture, woodlots, mixed farming, and livestock (USEPA, 2006). This ecoregion provides a key component of national energy resources as it contains the second largest coal reserve in the United States, and the largest reserve of bituminous coal (Varanka and Shaver, 2007). One of the primary reasons for change in the ecoregion is urbanization.

  16. Root characters of Lucerne (Medicago sativa L.) under rain-fed and irrigated conditions

    NASA Astrophysics Data System (ADS)

    Raza, Amir; Moghaddam, Ali; Loiskandl, Willibald; Friedel, Jürgen K.; Himmelbauer, Margaritta; Bodner, Gernot

    2010-05-01

    In organic farming, only limited use of selected fertilizers is allowed and plants have to meet their nutritional requirements through mobilization of nutrients provided by organic amendments, crop residue input within the rotation, and released from the soil reservoir. The crop varieties used in such systems shall be efficient in nutrient and water uptake. Root length, surface area and depth distribution are important root characters that demonstrate a potential for nutrient and water uptake. Detailed information on these root characters is lacking for Lucerne, one of the most important legume crop widely used in organic farming. A study was designed to compare three lucerne cultivars from different geographical origin viz. Niva, Mohajaren and Sitel for their root characters in two different sets of experiments planted under rain-fed and irrigated conditions in 2007. The irrigated experiment should provide root traits under potential growth conditions while the rain-fed experiment should highlight root characteristics under water limited conditions. The experiments were conducted on fields of the research station Groß Enzersdorf of the University or Natural Resources and Applied Life Sciences(BOKU), Vienna, Austria. Both experiments were laid out in α-lattice design with two replicates. At the end of vegetation period, root samples were taken for every 30 cm soil profile depth till the depth of 90 cm. From each plot, one sample was taken on the row and two samples between the rows using a cylindrical auger for sampling depth of 0 - 30, 30 - 60 and 60 - 90 cm. Root samples were washed out and analyzed with WinRhizo software to determine root length, surface area, root volume and average diameter. Results revealed that cultivars under rain-fed conditions had higher root length density and surface area than under irrigated conditions. The differences in root parameters estimated for each of the Lucerne cultivars are discussed.

  17. Rainwater harvesting and management in rainfed agricultural systems in sub-Saharan Africa - A review

    NASA Astrophysics Data System (ADS)

    Biazin, Birhanu; Sterk, Geert; Temesgen, Melesse; Abdulkedir, Abdu; Stroosnijder, Leo

    Agricultural water scarcity in the predominantly rainfed agricultural system of sub-Saharan Africa (SSA) is more related to the variability of rainfall and excessive non-productive losses, than the total annual precipitation in the growing season. Less than 15% of the terrestrial precipitation takes the form of productive ‘green’ transpiration. Hence, rainwater harvesting and management (RWHM) technologies hold a significant potential for improving rainwater-use efficiency and sustaining rainfed agriculture in the region. This paper outlines the various RWHM techniques being practiced in SSA, and reviews recent research results on the performance of selected practices. So far, micro-catchment and in situ rainwater harvesting techniques are more common than rainwater irrigation techniques from macro-catchment systems. Depending on rainfall patterns and local soil characteristics, appropriate application of in situ and micro-catchment techniques could improve the soil water content of the rooting zone by up to 30%. Up to sixfold crop yields have been obtained through combinations of rainwater harvesting and fertiliser use, as compared to traditional practices. Supplemental irrigation of rainfed agriculture through rainwater harvesting not only reduces the risk of total crop failure due to dry spells, but also substantially improves water and crop productivity. Depending on the type of crop and the seasonal rainfall pattern, the application of RWHM techniques makes net profits more possible, compared to the meagre profit or net loss of existing systems. Implementation of rainwater harvesting may allow cereal-based smallholder farmers to shift to diversified crops, hence improving household food security, dietary status, and economic return. The much needed green revolution and adaptations to climate change in SSA should blend rainwater harvesting ideals with agronomic principles. More efforts are needed to improve the indigenous practices, and to disseminate best

  18. Can rainfed agriculture adapt to uncertainty in availability of water in Indus Basin?

    NASA Astrophysics Data System (ADS)

    Jutla, A.; Sen, S.

    2015-12-01

    Understanding impacts of hydrological and climatological functions under changing climate on regional floods, droughts as well as agricultural commodities remain a serious challenge in tropical agricultural basins. These "tropical agricultural basins" are regions where: (i) the understanding on hydrologic functions (such as precipitation, soil moisture, evapotranspiration, surface runoff, vegetation) are not well established; (ii) increasing population is at the convergence of rural and urban boundaries; (iii) resilience and sustainability of the water resources under different climatic conditions is unknown; and, (iv) agriculture is the primary occupation for majority of the population. More than 95% of the farmed lands in tropical regions are rainfed and 60% of total agricultural production in South Asia relying on seasonal rainfall. Tropical regions frequently suffer from unexpected droughts and sudden flash floods, resulting in massive losses in human lives and affecting regional economy. Prediction of frequency, intensity and magnitude of floods in tropical regions is still a subject of debate and research. A clear example is from the massive floods in the Eastern Indus River in July 2010 that submerged 17 million acre of fertile cropland. Yet, seasonal droughts, such as 2014 rain deficits in Indus Basin, had no effects on annual crop yields - thus creating a paradox. Large amounts of groundwater is being used to supplement water needs for crops during drought conditions, leading to oversubscription of natural aquifers. Key reason that rainfed agriculture is relying heavily on groundwater is because of the uncertainty in timing and distribution of precipitation in the tropical regions, where such data are not routinely collected as well as the basins are transnational, thus limiting sharing of data. Assessment of availability of water for agricultural purposes a serious challenge in tropical regions. This study will provide a framework for using multi

  19. Understanding the nature of methane emission from rice ecosystems as basis of mitigation strategies

    SciTech Connect

    Buendia, L.V.; Neue, H.U.; Wassmann, R.

    1996-12-31

    Methane is considered as an important Greenhouse gas and rice fields are one of the major atmospheric methane sources. The paper aims to develop sampling strategies and formulate mitigation options based on diel (day and night) and seasonal pattern of methane emission. The study was conducted in 4 countries to measure methane flux using an automatic closed chamber system. A 24-hour bihourly methane emissions were continuously obtained during the whole growing season. Daily and seasonal pattern of methane fluxes from different rice ecosystems were evaluated. Diel pattern of methane emission from irrigated rice fields, in all sites, displayed similar pattern from planting to flowering. Fluxes at 0600, 1200, and 1800 h were important components of the total diel flux. A proposed sampling frequency to accurately estimate methane emission within the growing season was designed based on the magnitude of daily flux variation. Total methane emission from different ecosystems follow the order: deepwater rice > irrigated rice > rainfed rice. Application of pig manure increased total emission by 10 times of that without manure. Green manure application increased emission by 49% of that applied only with inorganic fertilizer. Removal of floodwater at 10 DAP and 35 DAP, within a period of 4 days, inhibited production and emission of methane. The level of variation in daily methane emission and seasonal emission pattern provides useful information for accurate determination of methane fluxes. Characterization of seasonal emission pattern as to ecologies, fertilizer amendments, and water management gives an idea of where to focus mitigation strategies for sustainable rice production.

  20. Climate Risk assessment and management in rainfed agriculture areas in Jordan

    NASA Astrophysics Data System (ADS)

    Khresat, Saeb

    2017-04-01

    Agricultural production is closely tied to climate, making agriculture one of the most climate-sensitive of all economic sectors. Figures and data from official resources and previous studies demonstrated that most of agricultural areas in Jordan were rainfed which made agriculture in the country more susceptible to climate change. The percentage of harvested to cultivated areas in those areas over the past ten years ranged from 45-55%, indicating a high risk associated with rainfed agriculture in Jordan. The anticipated increase in temperature and decrease in precipitation would adversely affect crops and water availability, critically influencing the patterns of future agricultural production, threatens livelihoods and keeps vulnerable people insecure. The anticipated increase in temperature and decrease in precipitation would result in 15-20% yield reduction for major field crops and vegetable crops by 2050 and 2070. This study was conducted to help in formulating action plans to adapt to climate change by assessing the risk from climate change on rainfed agriculture. The scenarios of climate change were used to assess the impact of climate change on rainfed agriculture. The overall risk level was based on possible land use shifts and crop yield under the most probable climate change scenarios. Accordingly, adaptive measures were proposed to reduce the impacts of climate change on agriculture in Jordan. The adaptation measures included the improvement of soil water storage to maximize plant water availability, the management of crop residue and tillage to conserve soil and water, the selection of drought-tolerant crop varieties, the expansion of water harvesting schemes through encouraging the farmers to adopt and apply the in-situ water harvesting systems (micro-catchment). Finally, the study emphasized the need for capacity building and awareness creation at the levels of farmers and extension staff. This would require the formulation of plans and strategies

  1. [Evapotranspiration characteristics and crop coefficient of rain-fed maize agroecosystem].

    PubMed

    Wang, Yu; Zhou, Guang-Sheng

    2010-03-01

    Based on the eddy covariance flux data, meteorological gradient data, and ecological observation data, an analysis was made on the diurnal and seasonal dynamics of evapotranspiration from a rain-fed maize agroecosystem in the growth season of 2007. The diurnal and seasonal dynamics of the evapotranspiration could be both expressed as parabola curve, with the peak values appeared at about 12:00 and July, respectively. The crop coefficient of the agroecosystem was mainly affected by leaf area index (LAI), air temperature, net radiation, and surface soil moisture content. A statistical model of crop coefficient on half-hour scale was constructed.

  2. Aerobic rice genotypes displayed greater adaptation to water-limited cultivation and tolerance to polyethyleneglycol-6000 induced stress.

    PubMed

    Sandhu, Nitika; Jain, Sunita; Battan, K R; Jain, R K

    2012-01-01

    Water scarcity and drought have seriously threatened traditional rice cultivation practices in several parts of the world including India. In the present investigation, experiments were conducted to see if the water-efficient aerobic rice genotypes developed at UAS, Bangalore (MAS25, MAS26 and MAS109) and IRRI, Philippines (MASARB25 and MASARB868), are endowed with drought tolerance or not. A set of these aerobic and five lowland high-yielding (HKR47 and PAU201, Taraori Basmati, Pusa1121 and Pusa1460) indica rice genotypes were evaluated for: (i) yield and yield components under submerged and aerobic conditions in field, (ii) root morphology and biomass under aerobic conditions in pots in the nethouse, (iii) PEG-6000 (0, -1, -2 and -3 bar) induced drought stress at vegetative stage using a hydroponic culture system and (iv) polymorphism for three SSR markers associated with drought resistance traits. Under submerged conditions, the yield of aerobic rice genotypes declined by 13.4-20.1 % whereas under aerobic conditions the yield of lowland indica/Basmati rice varieties declined by 23-27 %. Under water-limited conditions in pots, aerobic rice genotypes had 54-73.8 % greater root length and 18-60 % higher fresh root biomass compared to lowland indica rice varieties. Notably, root length of MASARB25 was 35 % shorter than MAS25 whereas fresh and dry root biomass of MASARB25 was 10 % and 64 % greater than MAS25. The lowland indica were more sensitive to PEG-stress with a score of 5.9-7.6 for Basmati and 6.1-6.7 for non-aromatic indica rice varieties, than the aerobic rice genotypes (score 2.7-3.3). A set of three microsatellite DNA markers (RM212, RM302 and RM3825) located on chromosome 1 which has been shown to be associated with drought resistance was investigated in the present study. Two of these markers (RM212 and RM302) amplified a specific allele in all the aerobic rice genotypes which were absent in lowland indica rice genotypes.

  3. Genetic diversity for mycorrhizal symbiosis and phosphate transporters in rice.

    PubMed

    Jeong, Kwanho; Mattes, Nicolas; Catausan, Sheryl; Chin, Joong Hyoun; Paszkowski, Uta; Heuer, Sigrid

    2015-11-01

    Phosphorus (P) is a major plant nutrient and developing crops with higher P-use efficiency is an important breeding goal. In this context we have conducted a comparative study of irrigated and rainfed rice varieties to assess genotypic differences in colonization with arbuscular mycorrhizal (AM) fungi and expression of different P transporter genes. Plants were grown in three different soil samples from a rice farm in the Philippines. The data show that AM symbiosis in all varieties was established after 4 weeks of growth under aerobic conditions and that, in soil derived from a rice paddy, natural AM populations recovered within 6 weeks. The analysis of AM marker genes (AM1, AM3, AM14) and P transporter genes for the direct Pi uptake (PT2, PT6) and AM-mediated pathway (PT11, PT13) were largely in agreement with the observed root AM colonization providing a useful tool for diversity studies. Interestingly, delayed AM colonization was observed in the aus-type rice varieties which might be due to their different root structure and might confer an advantage for weed competition in the field. The data further showed that P-starvation induced root growth and expression of the high-affinity P transporter PT6 was highest in the irrigated variety IR66 which also maintained grain yield under P-deficient field conditions.

  4. Drought-tolerant QTL qVDT11 leads to stable tiller formation under drought stress conditions in rice.

    PubMed

    Kim, Tae-Heon; Hur, Yeon-Jae; Han, Sang-Ik; Cho, Jun-Hyun; Kim, Kyung-Min; Lee, Jong-Hee; Song, You-Chun; Kwon, Yeong-Up; Shin, Dongjin

    2017-03-01

    Drought is an important limiting factor for rice production, but the genetic mechanisms of drought tolerance is poorly understood. Here, we screened 218 rice varieties to identify 32 drought-tolerant varieties. The variety Samgang exhibited strong drought tolerance and stable yield in rain-fed conditions and was selected for further study. To identify QTLs for drought tolerance, we examined visual drought tolerance (VDT) and relative water content (RWC) phenotypes in a doubled haploid (DH) population of 101 individuals derived from a cross between Samgang and Nagdong (a drought-sensitive variety). Three QTLs from Samgang were identified for VDT and explained 41.8% of the phenotypic variance. In particular, qVDT11 contributed 20.3% of the phenotypic variance for RWC. To determine QTL effects on drought tolerance in rain-fed paddy conditions, seven DH lines were selected according to the number of QTLs they contained. Of the drought-tolerance-associated QTLs, qVDT2 and qVDT6 did not affect tiller formation, but qVDT11 increased tiller number. Tiller formation was most stable when qVDT2 and qVDT11 were combined. DH lines with both of these drought-tolerance-associated QTLs exhibited the most stable tiller formation. Together, these results suggest that qVDT11 is important for drought tolerance and stable tiller formation in rain-fed paddy fields. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  5. Yield and Production Gaps in Rainfed Wheat, Barley, and Canola in Alberta

    PubMed Central

    Chapagain, Tejendra; Good, Allen

    2015-01-01

    Improving crop yields are essential to meet the increasing pressure of global food demands. The loss of high quality land, the slowing in annual yield increases of major cereals, increasing fertilizer use, and the effect of this on the environment all indicate that we need to develop new strategies to increase grain yields with less impact on the environment. One strategy that could help address this concern is by narrowing the yield gaps of major crops using improved genetics and management. The objective of this study was to determine wheat (Triticum spp. L.), barley (Hordeum vulgare L.), and canola (Brassica napus L.) yields and production gaps in Alberta. We used 10 years of data (2005–2014) to understand yield variability and input efficiency at a farmers’ specified level of management, and the yield potential under optimal management to suggest appropriate pathways for closing yield gaps. Significant management gaps were observed between attainable and actual yields of rainfed wheat (24%), barley (25%), and canola (30%). In addition, genetic gaps (i.e., gaps due to genetic selection) in wheat, barley, and canola were 18, 12, and 5%, respectively. Genetic selection with optimal crop management could increase yields of wheat, barley, and canola significantly, with estimated yield gains of 3.42, 1.92, and 1.65 million tons, respectively, each year under rainfed conditions in Alberta. This paper identifies yield gaps and offers suggestions to improve efficiency in crop production. PMID:26635824

  6. From rainfed agriculture to stress-avoidance irrigation: II. Sustainability, crop yield, and profitability

    NASA Astrophysics Data System (ADS)

    Vico, Giulia; Porporato, Amilcare

    2011-02-01

    The optimality of irrigation strategies may be sought with respect to a number of criteria, including water requirements, crop yield, and profitability. To explore the suitability of different demand-based irrigation strategies, we link the probabilistic description of irrigation requirements under stochastic hydro-climatic conditions, provided in a companion paper [Vico G, Porporato A. From rainfed agriculture to stress-avoidance irrigation: I. A generalized irrigation scheme with stochastic soil moisture. Adv Water Resour 2011;34(2):263-71], to crop-yield and economic analyses. Water requirements, application efficiency, and investment costs of different irrigation methods, such as surface, sprinkler and drip irrigation systems, are described via a unified conceptual and theoretical approach, which includes rainfed agriculture and stress-avoidance irrigation as extreme cases. This allows us to analyze irrigation strategies with respect to sustainability, productivity, and economic return, using the same framework, and quantify them as a function of climate, crop, and soil parameters. We apply our results to corn ( Zea mays), a food staple and biofuel source, which is currently mainly irrigated through surface systems. As our analysis shows, micro-irrigation maximizes water productivity, but more traditional solutions may be more profitable at least in some contexts.

  7. Sustainable land management practices as providers of several ecosystem services under rainfed Mediterranean agroecosystems

    NASA Astrophysics Data System (ADS)

    Almagro, María; de Vente, Joris; Boix-Fayós, Carolina; García-Franco, Noelia; Melgares de Aguilar, Javier; González, David; Solé-Benet, Albert; Martínez-Mena, María

    2015-04-01

    Little is known about the multiple impacts of sustainable land management practices on soil and water conservation, carbon sequestration, mitigation of global warming, and crop yield productivity in semiarid Mediterranean agroecosystems. We hypothesized that a shift from intensive tillage to more conservative tillage management practices (reduced tillage optionally combined with green manure) leads to an improvement in soil structure and quality and will reduce soil erosion and enhance carbon sequestration in semiarid Mediterranean rainfed agroecosystems. To test the hypothesis, we assessed the effects of different tillage treatments (conventional (CT), reduced (RT), reduced tillage combined with green manure (RTG), and no tillage (NT)) on soil structure and soil water content, runoff and erosion control, soil CO2 emissions, crop yield and carbon sequestration in two semiarid agroecosystems with organic rainfed almond in the Murcia Region southeast Spain). It was found that reduction and suppression of tillage under almonds led to an increase in soil water content in both agroecosystems. Crop yields ranged from 775 to 1766 kg ha-1 between tillage 18 treatments, but we did not find a clear relation between soil water content and crop yield. RT and RTG treatments showed lower soil erosion rates and higher crop yields of almonds than under CT treatment. Overall, higher soil organic carbon contents and aggregate stability were observed under RTG treatment than under RT or CT treatment. It is concluded that conversion from CT to RTG is suitable to increase carbon inputs without enhancing soil CO2 emissions in semiarid Mediterranean agroecosystems.

  8. Drought, agricultural adaptation, and sociopolitical collapse in the Maya Lowlands

    PubMed Central

    Douglas, Peter M. J.; Pagani, Mark; Canuto, Marcello A.; Brenner, Mark; Hodell, David A.; Eglinton, Timothy I.; Curtis, Jason H.

    2015-01-01

    Paleoclimate records indicate a series of severe droughts was associated with societal collapse of the Classic Maya during the Terminal Classic period (∼800–950 C.E.). Evidence for drought largely derives from the drier, less populated northern Maya Lowlands but does not explain more pronounced and earlier societal disruption in the relatively humid southern Maya Lowlands. Here we apply hydrogen and carbon isotope compositions of plant wax lipids in two lake sediment cores to assess changes in water availability and land use in both the northern and southern Maya lowlands. We show that relatively more intense drying occurred in the southern lowlands than in the northern lowlands during the Terminal Classic period, consistent with earlier and more persistent societal decline in the south. Our results also indicate a period of substantial drying in the southern Maya Lowlands from ∼200 C.E. to 500 C.E., during the Terminal Preclassic and Early Classic periods. Plant wax carbon isotope records indicate a decline in C4 plants in both lake catchments during the Early Classic period, interpreted to reflect a shift from extensive agriculture to intensive, water-conservative maize cultivation that was motivated by a drying climate. Our results imply that agricultural adaptations developed in response to earlier droughts were initially successful, but failed under the more severe droughts of the Terminal Classic period. PMID:25902508

  9. Drought, agricultural adaptation, and sociopolitical collapse in the Maya Lowlands

    NASA Astrophysics Data System (ADS)

    Douglas, Peter M. J.; Pagani, Mark; Canuto, Marcello A.; Brenner, Mark; Hodell, David A.; Eglinton, Timothy I.; Curtis, Jason H.

    2015-05-01

    Paleoclimate records indicate a series of severe droughts was associated with societal collapse of the Classic Maya during the Terminal Classic period (∼800-950 C.E.). Evidence for drought largely derives from the drier, less populated northern Maya Lowlands but does not explain more pronounced and earlier societal disruption in the relatively humid southern Maya Lowlands. Here we apply hydrogen and carbon isotope compositions of plant wax lipids in two lake sediment cores to assess changes in water availability and land use in both the northern and southern Maya lowlands. We show that relatively more intense drying occurred in the southern lowlands than in the northern lowlands during the Terminal Classic period, consistent with earlier and more persistent societal decline in the south. Our results also indicate a period of substantial drying in the southern Maya Lowlands from ∼200 C.E. to 500 C.E., during the Terminal Preclassic and Early Classic periods. Plant wax carbon isotope records indicate a decline in C4 plants in both lake catchments during the Early Classic period, interpreted to reflect a shift from extensive agriculture to intensive, water-conservative maize cultivation that was motivated by a drying climate. Our results imply that agricultural adaptations developed in response to earlier droughts were initially successful, but failed under the more severe droughts of the Terminal Classic period.

  10. Drought, agricultural adaptation, and sociopolitical collapse in the Maya Lowlands.

    PubMed

    Douglas, Peter M J; Pagani, Mark; Canuto, Marcello A; Brenner, Mark; Hodell, David A; Eglinton, Timothy I; Curtis, Jason H

    2015-05-05

    Paleoclimate records indicate a series of severe droughts was associated with societal collapse of the Classic Maya during the Terminal Classic period (∼800-950 C.E.). Evidence for drought largely derives from the drier, less populated northern Maya Lowlands but does not explain more pronounced and earlier societal disruption in the relatively humid southern Maya Lowlands. Here we apply hydrogen and carbon isotope compositions of plant wax lipids in two lake sediment cores to assess changes in water availability and land use in both the northern and southern Maya lowlands. We show that relatively more intense drying occurred in the southern lowlands than in the northern lowlands during the Terminal Classic period, consistent with earlier and more persistent societal decline in the south. Our results also indicate a period of substantial drying in the southern Maya Lowlands from ∼200 C.E. to 500 C.E., during the Terminal Preclassic and Early Classic periods. Plant wax carbon isotope records indicate a decline in C4 plants in both lake catchments during the Early Classic period, interpreted to reflect a shift from extensive agriculture to intensive, water-conservative maize cultivation that was motivated by a drying climate. Our results imply that agricultural adaptations developed in response to earlier droughts were initially successful, but failed under the more severe droughts of the Terminal Classic period.

  11. Elastic Thickness Estimates for the Northern Lowlands of Mars

    NASA Astrophysics Data System (ADS)

    Hoogenboom, T.; Smrekar, S.

    2005-05-01

    The northern hemisphere lowlands of Mars cover approximately one-third of the surface of the planet. While crustal remnant magnetization is very strong in much of the Martian highlands, in contrast only a few low amplitude anomalies occur in the lowlands [Acuna et al., 1999]. The scarcity of magnetic anomalies in the lowlands remains unexplained. Crater counts for the northern lowlands basement based on analyses of high-resolution MOLA maps show that they are comparable in age to the southern highlands [Frey, 2004]. Since the basement age is so similar, it seems unlikely that the dynamo could have been active during formation of the highlands but not the lowlands. Topography and gravity measured by the Mars Global Surveyor have enabled the determination of elastic thickness (Te) estimates in the highlands [e.g. McGovern et al., 2002]. However, there have been no successful estimates in the Northern lowlands with the exception of Utopia basin [Zuber et al., 2002]. The failure is assumed due to insufficient power in the topography. Although the northern plains have clearly been eroded, we find that for selected Northern lowland regions, the power in the topography is smaller but comparable to areas of the southern highlands, previously used to obtain Te estimates. Previously, inversions based on isostatic response methods using eroded topography yielded incorrect results [Forsyth, 1985]. McKenzie and Fairhead [1997] find that Forsyths method can only be used to estimate Te where the power of the gravity from the uncompensated topography is comparable to that of the observed gravity at short wavelengths. If this condition is not satisfied, because the short-wavelength gravity is dominated by sub-surface loads and not by the topography, the estimated value of Te provides an upper bound. We use a multi-taper approach that has been successful at minimizing this bias for eroded cratons on Earth [Swain & Kirby, 2003]. In this study we perform detailed modeling of the

  12. Growing season variability in carbon dioxide exchange of irrigated and rainfed soybean in the southern United States

    USDA-ARS?s Scientific Manuscript database

    Measurement of carbon dynamics of soybean (Glycine max L.) ecosystems outside Corn Belt of the United States (U.S.) is lacking. This study reports carbon dioxide (CO2) fluxes from a rainfed soybean field in El Reno, Oklahoma and an irrigated soybean field in Stoneville, Mississippi during the 2016 g...

  13. Evaluation of agronomic traits and spectral reflectance in Pacific Northwest winter wheat under rain-fed and irrigated conditions

    USDA-ARS?s Scientific Manuscript database

    The US Pacific Northwest (PNW) is a major winter wheat mega-environment characterized by a high latitude and a Mediterranean-like climate. Wheat production is predominantly rain-fed and often subject to low soil moisture. As result, discovery and introgression of drought-adaptive traits in modern cu...

  14. Wind erosion and PM10 emission affected by tillage in the world’s driest rainfed wheat region

    USDA-ARS?s Scientific Manuscript database

    The Horse Heaven Hills of south-central Washington is the driest rainfed wheat growing region in the world. Low precipitation, high winds, poorly aggregated soils, sparse residue cover, and a tillage-based winter wheat (Triticum aestivum L.) – summer fallow (WW-SF) cropping system often combine to c...

  15. Water for food and nature in drought-prone tropics: vapour shift in rain-fed agriculture.

    PubMed Central

    Rockström, Johan

    2003-01-01

    This paper quantifies the eco-hydrological challenge up until 2050 of producing food in balance with goods and services generated by water-dependent ecosystems in nature. Particular focus is given to the savannah zone, covering 40% of the land area in the world, where water scarcity constitutes a serious constraint to sustainable development. The analysis indicates an urgent need for a new green revolution, which focuses on upgrading rain-fed agriculture. Water requirements to produce adequate diets for humans are shown to be relatively generic irrespective of hydro-climate, amounting to a global average of 1,300 m(3) cap(-1) yr(-1). Present food production requires an estimated 6,800 km(3) yr(-1) of consumptive green water (5,000 km(3) yr(-1) in rain-fed agriculture and 1,800 km(3) yr(-1) from irrigated crops). Without considering water productivity gains, an additional 5,800 km(3) yr(-1) of water is needed to feed a growing population in 2,050 and eradicate malnutrition. It is shown that the bulk of this water will be used in rain-fed agriculture. A dynamic analysis of water productivity and management options indicates that large 'crop per drop' improvements can be achieved at the farm level. Vapour shift in favour of productive green water flow as crop transpiration could result in relative water savings of 500 km(3) yr(-1) in semi-arid rain-fed agriculture. PMID:14728794

  16. N2O emission characteristics and its affecting factors in rain-fed potato fields in Wuchuan County, China

    NASA Astrophysics Data System (ADS)

    Wang, Liwei; Wang, Cheng; Pan, Zhihua; Xu, Hui; Gao, Lin; Zhao, Peiyi; Dong, Zhiqiang; Zhang, Jingting; Cui, Guohui; Wang, Sen; Han, Guolin; Zhao, hui

    2017-05-01

    Representing an important greenhouse gas, nitrous oxide (N2O) emission from cultivated land is a hot topic in current climate change research. This study examined the influences of nitrogen fertilisation, temperature and soil moisture on the ammonia monooxygenase subunit A ( amoA) gene copy numbers and N2O emission characteristics. The experimental observation of N2O fluxes was based on the static chamber-gas chromatographic method. The ammonia-oxidising bacteria (AOB) and ammonia-oxidising archaea (AOA) gene copy numbers in different periods were measured by real-time polymerase chain reaction (PCR). The results indicated that rain-fed potato field was a N2O source, and the average annual N2O emission was approximately 0.46 ± 0.06 kgN2O-N/ha/year. N2O emissions increased significantly with increase in fertilisation, temperatures below 19.6 °C and soil volumetric water content under 15%. Crop rotation appreciably decreases N2O emissions by 34.4 to 52.4% compared to continuous cropping in rain-fed potato fields. The significant correlation between N2O fluxes and AOB copy numbers implied that N2O emissions were primarily controlled by AOB in rain-fed potato fields. The research has important theoretical and practical value for understanding N2O emissions from rain-fed dry farmland fields.

  17. N2O emission characteristics and its affecting factors in rain-fed potato fields in Wuchuan County, China

    NASA Astrophysics Data System (ADS)

    Wang, Liwei; Wang, Cheng; Pan, Zhihua; Xu, Hui; Gao, Lin; Zhao, Peiyi; Dong, Zhiqiang; Zhang, Jingting; Cui, Guohui; Wang, Sen; Han, Guolin; Zhao, hui

    2016-12-01

    Representing an important greenhouse gas, nitrous oxide (N2O) emission from cultivated land is a hot topic in current climate change research. This study examined the influences of nitrogen fertilisation, temperature and soil moisture on the ammonia monooxygenase subunit A (amoA) gene copy numbers and N2O emission characteristics. The experimental observation of N2O fluxes was based on the static chamber-gas chromatographic method. The ammonia-oxidising bacteria (AOB) and ammonia-oxidising archaea (AOA) gene copy numbers in different periods were measured by real-time polymerase chain reaction (PCR). The results indicated that rain-fed potato field was a N2O source, and the average annual N2O emission was approximately 0.46 ± 0.06 kgN2O-N/ha/year. N2O emissions increased significantly with increase in fertilisation, temperatures below 19.6 °C and soil volumetric water content under 15%. Crop rotation appreciably decreases N2O emissions by 34.4 to 52.4% compared to continuous cropping in rain-fed potato fields. The significant correlation between N2O fluxes and AOB copy numbers implied that N2O emissions were primarily controlled by AOB in rain-fed potato fields. The research has important theoretical and practical value for understanding N2O emissions from rain-fed dry farmland fields.

  18. Genetic variation of rice (Oryza sativa L.) germplasm in Myanmar based on genomic compositions of DNA markers

    PubMed Central

    Wunna; Watanabe, Kazuo N.; Ohsawa, Ryo; Obara, Mitsuhiro; Yanagihara, Seiji; Aung, Pa Pa; Fukuta, Yoshimichi

    2016-01-01

    The genetic diversity of 175 rice accessions from Myanmar, including landraces and improved types from upland and lowland ecosystems in five different areas—Western (hilly), Northern (mountainous), North and South-eastern (plateau), and Southern (plain)—was evaluated on the basis of polymorphism data for 65 DNA markers and phenol reactions. On the basis of the DNA polymorphism data, high genetic diversity was confirmed to conserve in the accessions from each ecosystem and area. And the accessions were classified into two cluster groups I and II, which corresponded to Indica Group and Japonica Group, respectively. Cluster group I accessions were distributed mainly in upland ecosystems; group II were distributed in lowland in the Southern area, and the distributions of dominant groups differed among areas. Rice germplasm in Myanmar has maintained high genetic diversity among ecosystems and areas. This information will be used for advanced studies in germplasm and rice breeding in Myanmar. PMID:28163592

  19. Growing season variability in carbon dioxide exchange of irrigated and rainfed soybean in the southern United States.

    PubMed

    Wagle, Pradeep; Gowda, Prasanna H; Anapalli, Saseendran S; Reddy, Krishna N; Northup, Brian K

    2017-09-01

    Measurement of carbon dynamics of soybean (Glycine max L.) ecosystems outside Corn Belt of the United States (U.S.) is lacking. This study examines the seasonal variability of net ecosystem CO2 exchange (NEE) and its components (gross primary production, GPP and ecosystem respiration, ER), and relevant controlling environmental factors between rainfed (El Reno, Oklahoma) and irrigated (Stoneville, Mississippi) soybean fields in the southern U.S. during the 2016 growing season. Grain yield was about 1.6tha(-1) for rainfed soybean and 4.9tha(-1) for irrigated soybean. The magnitudes of diurnal NEE (~2-weeks average) reached seasonal peak values of -23.18 and -34.78μmolm(-2)s(-1) in rainfed and irrigated soybean, respectively, approximately two months after planting (i.e., during peak growth). Similar thresholds of air temperature (Ta, slightly over 30°C) and vapor pressure deficit (VPD, ~2.5kPa) for NEE were observed at both sites. Daily (7-day average) NEE, GPP, and ER reached seasonal peak values of -4.55, 13.54, and 9.95gCm(-2)d(-1) in rainfed soybean and -7.48, 18.13, and 14.93gCm(-2)d(-1) in irrigated soybean, respectively. The growing season (DOY 132-243) NEE, GPP, and ER totals were -54, 783, and 729gCm(-2), respectively, in rainfed soybean. Similarly, cumulative NEE, GPP, and ER totals for DOY 163-256 (flux measurement was initiated on DOY 163, missing first 45days after planting) were -291, 1239, and 948gCm(-2), respectively, in irrigated soybean. Rainfed soybean was a net carbon sink for only two months, while irrigated soybean appeared to be a net carbon sink for about three months. However, grain yield and the magnitudes and seasonal sums of CO2 fluxes for irrigated soybean in this study were comparable to those for soybean in the U.S. Corn Belt, but they were lower for rainfed soybean. Published by Elsevier B.V.

  20. Estimating evapotranspiration in different rain-fed peatlands from groundwater level changes

    NASA Astrophysics Data System (ADS)

    Dettmann, Ullrich; Maurer, Eike; Bechtold, Michel; Brümmer, Christian; Tiemeyer, Bärbel

    2014-05-01

    Biogeochemical processes in peatlands are strongly controlled by the hydrological conditions of these environments. One of the key parameters controlling the water balance is the evapotranspiration, which can be calculated e.g. by the FAO crop reference evapotranspiration or the Penman-Monteith equation as a function of atmospheric conditions and plant specific parameters. These parameters are well investigated for agricultural crops and forests but poorly for most peatland vegetation types. Direct measurement of the evapotranspiration is possible with weighing lysimeters or the eddy-covariance technique, but expensive and time consuming. In many peatlands and riparian areas groundwater table changes are characterized by diurnal fluctuations (daytime decline, night-time recovery) caused by the evapotranspiration and groundwater recharge. White introduced 1932 a method to calculate the evapotranspiration from these diurnal fluctuations. In contrast to traditional evapotranspiration models only a small number of variables need to be measured (groundwater level changes, possibly precipitation) or calculated (specific yield). Over the last decades, several studies and modifications of the White method have been published. Several authors showed the applicability of the method for riparian areas and fens, but this relies on the assumption of a constant recharge over the whole day. As there is no groundwater inflow at rain-fed peatlands, recovery during night-time can only result from redistribution in the soil profile or from lateral flow processes within the peatland. Thus, approaches to calculate evapotranspiration from diurnal groundwater fluctuations used to date need to be adapted. Based on 50 hydrographs measured in 6 rain-fed peatlands in Germany characterized by different soil properties, land use and vegetation, we systematically analyzed diurnal patterns of the groundwater levels. These patterns were spatially and temporally very variable. At some sites, the

  1. A global map of rainfed cropland areas (GMRCA) at the end of last millennium using remote sensing

    USGS Publications Warehouse

    Biradar, C.M.; Thenkabail, P.S.; Noojipady, P.; Li, Y.; Dheeravath, V.; Turral, H.; Velpuri, M.; Gumma, M.K.; Gangalakunta, O.R.P.; Cai, X.L.; Xiao, X.; Schull, M.A.; Alankara, R.D.; Gunasinghe, S.; Mohideen, S.

    2009-01-01

    The overarching goal of this study was to produce a global map of rainfed cropland areas (GMRCA) and calculate country-by-country rainfed area statistics using remote sensing data. A suite of spatial datasets, methods and protocols for mapping GMRCA were described. These consist of: (a) data fusion and composition of multi-resolution time-series mega-file data-cube (MFDC), (b) image segmentation based on precipitation, temperature, and elevation zones, (c) spectral correlation similarity (SCS), (d) protocols for class identification and labeling through uses of SCS R2-values, bi-spectral plots, space-time spiral curves (ST-SCs), rich source of field-plot data, and zoom-in-views of Google Earth (GE), and (e) techniques for resolving mixed classes by decision tree algorithms, and spatial modeling. The outcome was a 9-class GMRCA from which country-by-country rainfed area statistics were computed for the end of the last millennium. The global rainfed cropland area estimate from the GMRCA 9-class map was 1.13 billion hectares (Bha). The total global cropland areas (rainfed plus irrigated) was 1.53 Bha which was close to national statistics compiled by FAOSTAT (1.51 Bha). The accuracies and errors of GMRCA were assessed using field-plot and Google Earth data points. The accuracy varied between 92 and 98% with kappa value of about 0.76, errors of omission of 2-8%, and the errors of commission of 19-36%. ?? 2008 Elsevier B.V.

  2. AmeriFlux US-Ne3 Mead - rainfed maize-soybean rotation site

    DOE Data Explorer

    Suyker, Andy [University of Nebraska - Lincoln

    2016-01-01

    This is the AmeriFlux version of the carbon flux data for the site US-Ne3 Mead - rainfed maize-soybean rotation site. Site Description - The study site is one of three fields (all located within 1.6 km of each other) at the University of Nebraska Agricultural Research and Development Center near Mead, Nebraska. While the other two sites are equipped with irrigation systems, this site relies on rainfall. A tillage operation (disking) was done just prior to the 2001 planting to homogenize the top 0.1 m of soil, incorporate P and K fertilizers, as well as previously accumulated surface residues. Since initiation of the study in 2001, this site has been under no-till management.

  3. Restoration of lowland streams: an introduction

    USGS Publications Warehouse

    Osborne, L.L.; Bayley, P.B.; Higler, L.W.G.; Statzner, B.; Triska, F.; Iverson, T. Moth

    1993-01-01

    1 This paper introduces the Lowland Streams Restoration Workshop that was held in Lund, Sweden in August 1991.2 Attenders at the Workshop participated in working groups which discussed and reported on the state of knowledge of stream restoration and identified critical areas of information need. Currently, most restoration efforts are emission-orientated (i.e. waste-water management), while the imitation of the geomorphology or of the riparian vegetation of a quasi-natural or natural reference channel receives less attention.3 Successful stream restoration requires a multidisciplinary approach within a holistic system framework. Monitoring the outcome of past, existing and future steam-restoration projects is required for information on the feasibility of alternative techniques and approaches.4 It was recommended that systems in pristine condition serve as a point of reference and not as a goal for most stream restoration projects. Restoration goals must be carefully defined so that everyone at every level understands the aim of the project. At the very least, all restoration programmes should consider geomorphic, hydrological, biological, aesthetic, and water quality aspects of the system.5 Restoration programmes should aim to create a system with a stable channel, or a channel in dynamic equilibrium that supports a self-sustaining and functionally diverse community assemblage; it should not concentrate on one species or group, except at the local level. Preserving the terrestrial -aquatic interface by setting aside riparian land corridors is critical to all stages of restoration. Additional information on the temporal and regional variability in important system processes and functions is needed.

  4. Genetic diversity and structure in hill rice (Oryza sativa L.) landraces from the North-Eastern Himalayas of India.

    PubMed

    Roy, Somnath; Marndi, B C; Mawkhlieng, B; Banerjee, A; Yadav, R M; Misra, A K; Bansal, K C

    2016-07-13

    Hill rices (Oryza sativa L.) are direct seeded rices grown on hill slopes of different gradients. These landraces have evolved under rainfed and harsh environmental conditions and may possess genes governing adaptation traits such as tolerance to cold and moisture stress. In this study, 64 hill rice landraces were collected from the state of Arunachal Pradesh of North-Eastern region of India, and assessed by agro-morphological variability and microsatellite markers polymorphism. Our aim was to use phenotypic and genetic diversity data to understand the basis of farmers' classification of hill rice landraces into two groups: umte and tening. Another goal was to understand the genetic differentiation of hill rices into Indica or japonica subspecies. According to farmers' classification, hill rices were categorized into two groups: umte (large-grained, late maturing) and tening (small-grained, early maturing). We did not find significant difference in days to 50 % flowering between the groups. Principal component analysis revealed that two groups can be distinguished on the basis of kernel length-to-width ration (KLW), kernel length (KL), grain length (GrL), grain length-to-width ration (GrLW) and plant height (Ht). Stepwise canonical discriminant analysis identified KL and Ht as the main discriminatory characters between the cultivar groups. Genetic diversity analysis with 35 SSR markers revealed considerable genetic diversity in the hill rice germplasm (gene diversity: 0.66; polymorphism information content: 0.62). Pair-wise allelic difference between umte and tening groups was not statistically significant. The model-based population structure analysis showed that the hill rices were clustered into two broad groups corresponding to Indica and Japonica. The geographic distribution and cultivars grouping of hill rices were not congruent in genetic clusters. Both distance- and model-based approaches indicated that the hill rices were predominantly japonica or

  5. Morphological and physiological responses of lowland purple nutsedge (Cyperus rotundus L.) to flooding

    PubMed Central

    Fuentes, Rolly G.; Baltazar, Aurora M.; Merca, Florinia E.; Ismail, Abdelbagi M.; Johnson, David E.

    2010-01-01

    Background and aims Purple nutsedge (Cyperus rotundus L.) is a major weed of upland crops and vegetables. Recently, a flood-tolerant ecotype evolved as a serious weed in lowland rice. This study attempted to establish the putative growth and physiological features that led to this shift in adaptation. Methodology Tubers of upland C. rotundus (ULCR) and lowland C. rotundus (LLCR) ecotypes were collected from their native habitats and maintained under the respective growth conditions in a greenhouse. Five experiments were conducted to assess the variation between the two ecotypes in germination, growth and tuber morphology when grown in their native or ‘switched’ conditions. Carbohydrate storage and mobilization, and variation in anaerobic respiration under hypoxia were compared. Principal results Tubers of LLCR were larger than those of ULCR, with higher carbohydrate content, and larger tubers developed with increasing floodwater depth. Stems of LLCR had larger diameter and proportionally larger air spaces than those of ULCR: a method of aerating submerged plant parts. The LLCR ecotype can also mobilize and use carbohydrate reserves under hypoxia, and it maintained relatively lower and steadier activity of alcohol dehydrogenase (ADH) as a measure of sustained anaerobic respiration. In contrast, ADH activity in ULCR increased faster upon a shift to hypoxia and then sharply decreased, suggesting depletion of available soluble sugar substrates. The LLCR ecotype also maintained lower lactate dehydrogenase activity under flooded conditions, which could reduce chances of cellular acidosis. Conclusions These adaptive traits in the LLCR ecotype were expressed constitutively, but some of them, such as tuber growth and aerenchyma development, are enhanced with stress severity. The LLCR ecotype attained numerous adaptive traits that could have evolved as a consequence of natural evolution or repeated management practices, and alternative strategies are necessary because

  6. Asiatic cotton can generate similar economic benefits to Bt cotton under rainfed conditions.

    PubMed

    Romeu-Dalmau, Carla; Bonsall, Michael B; Willis, Katherine J; Dolan, Liam

    2015-06-01

    American cotton (Gossypium hirsutum L.), transformed with Bacillus thuringiensis Cry genes (Bt G. hirsutum) that confer resistance to lepidopteran pests, is extensively cultivated worldwide. In India, transgenic Bt G. hirsutum was commercially released in 2002 and by 2014 95% of farmers had adopted Bt G. hirsutum(1). The economic benefits of Bt G. hirsutum over non-Bt G. hirsutum are well documented and include increase in yields, increase in farmers' net revenue and reduction in pesticide application against lepidopteran pests(2-9). However, it is unclear to what extent irrigation influences the performance of Bt G. hirsutum on smallholder farming in India, and if, in the absence of irrigation, growing Bt G. hirsutum provides greater economic benefits for Indian smallholder farmers compared with growing the Asiatic cotton Gossypium arboreum L. Here, we compare the economic impact of growing Bt G. hirsutum with growing G. arboreum under rainfed conditions in the Indian state of Maharashtra, and show that G. arboreum can generate similar net revenue, and thus similar economic benefits for smallholder farmers compared with growing Bt G. hirsutum. We also compare the economic impact of growing Bt G. hirsutum under rainfed conditions with growing Bt G. hirsutum under irrigated conditions and show that even though Bt G. hirsutum yields increase with irrigation, the net revenue does not significantly increase because farmers using irrigation spend significantly more than farmers growing Bt G. hirsutum without irrigation. We conclude that our data provide a broader insight into how socio-economic data needs to be incorporated into agro-ecological data when planning strategies to improve cotton farming in India.

  7. A Decision Support System for Climate Change Adaptation in Rainfed Sectors of Agriculture for Central Europe

    NASA Astrophysics Data System (ADS)

    Mátyás, Csaba; Berki, Imre; Drüszler, Áron; Eredics, Attila; Gálos, Borbála; Illés, Gábor; Móricz, Norbert; Rasztovits, Ervin; Czimber, Kornél

    2013-04-01

    • Background and aims: Rainfed sectors of agriculture such as nature-close forestry, non-irrigated agriculture and animal husbandry on nature-close pastures are threatened by projected climate change especially in low-elevation regions in Southeast Europe, where precipitation is the limiting factor of production and ecosystem stability. Therefore the importance of complex, long term management planning and of land use optimization is increasing. The aim of the Decision Support System under development is to raise awareness and initiate preparation for frequency increase of extreme events, disasters and economic losses in the mentioned sectors. • Services provided: The Decision Support System provides GIS-supported information about the most important regional and local risks and mitigation options regarding climate change impacts, projected for reference periods until 2100 (e.g. land cover/use and expectable changes, potential production, water and carbon cycle, biodiversity and other ecosystem services, potential pests and diseases, tolerance limits etc.). The projections are referring first of all on biological production (natural produce), but the System includes also social and economic consequences. • Methods: In the raster based system, the latest image processing technology is used. We apply fuzzy membership functions, Support Vector Machine and Maximum Likelihood classifier. The System is developed in the first step for a reference area in SW Hungary (Zala county). • Novelty: The coherent, fine-scale regional system integrates the basic information about present and projected climates, extremes, hydrology and soil conditions and expected production potential for three sectors of agriculture as options for land use and conservation. • Funding: The development of the Decision Support System "Agrárklíma" is supported by TÁMOP-4.2.2.A-11/1/KONV and 4.2.2.B-10/1-2010-0018 "Talentum" joint EU-national research projects. Keywords: climate change

  8. Potential impact of climate change on rainfed agriculture of a semi-arid basin in Jordan

    NASA Astrophysics Data System (ADS)

    Al-Bakri, Jawad; Suleiman, Ayman; Abdulla, Fayez; Ayad, Jamal

    Rainfed agriculture in Jordan is one of the most vulnerable sectors to climate change, as the available water and land resources are limited and most of the country’s land is arid. In this study, a crop simulation model (DSSAT) was used to assess the impact of different climate change scenarios on rainfed wheat and barley in the Yarmouk basin in Jordan. Analysis of observed crop data showed differences between cultivated and harvested areas for both crops in the study area with variations among years. Results from DSSAT model for years showed that it was able to capture the trend of yield over the years realistically well. The model predicted an average yield of wheat of 1176 kg ha -1, which was close to the average (1173 kg ha -1) obtained from the data of department of statistics (DOS), and an average predicted yield of barley was 927 kg ha -1 while the DOS average was 922 kg ha -1, with higher RMSE for barley (476 kg ha -1) than for wheat (319 kg ha -1). Results for predicting future yield of both crops showed that the responses of wheat and barley were different under different climate change scenarios. The reduction of rainfall by 10-20% reduced the expected yield by 4-8% for barley and 10-20% for wheat, respectively. The increase in rainfall by 10-20% increased the expected yield by 3-5% for barley and 9-18% for wheat, respectively. The increase of air temperature by 1, 2, 3 and 4 °C resulted in deviation from expected yield by -14%, -28%, -38% and -46% for barley and -17%, +4%, +43% and +113% for wheat, respectively. These results indicated that barley would be more negatively affected by the climate change scenarios and therefore adaptation plans should prioritize the arid areas cultivated with this crop.

  9. Carbon budget of a rainfed spring maize cropland with straw returning on the Loess Plateau, China.

    PubMed

    Gao, Xiang; Gu, Fengxue; Hao, Weiping; Mei, Xurong; Li, Haoru; Gong, Daozhi; Mao, Lili; Zhang, Zuguang

    2017-05-15

    Assessing the carbon budget of rainfed agricultural ecosystems is a vital component in the process of estimating the global carbon balance. We used eddy covariance techniques combined with soil respiration measurements to estimate the carbon budget of a rainfed spring maize field where straw returning was practiced, on the Loess Plateau, China, during 2012-2014. Carbon fluxes and their components (except heterotrophic respiration, Rh) exhibited single-peak seasonal patterns, and linear relationships were found between daily gross primary productivity (GPP) and net ecosystem exchange (NEE), and between daily GPP and ecosystem respiration (Re), with goodness of fit value of 0.96 and 0.85, respectively. The green leaf area index was the most important factor controlling seasonal variations in daily NEE, Re, and GPP during the growing season, followed by photosynthetically active radiation and air temperature (Ta). Daily Re was mainly controlled by air temperature during the non-growing season, when Re accounted for only ~17% of the annual Re due to winter temperatures. Growing season plant respiration (Rp) was the most important source of carbon emissions from the maize field, with aboveground plant respiration being the major part of Rp. Rh accounted for ~60% of total soil respiration. Only ~60% of the annual GPP was lost as Re, resulting in an average annual net CO2 uptake of 509gCm(-2). Taking into account carbon exported (483gCm(-2)) and carbon imported (10gCm(-2)), the average annual net biome productivity was 37gCm(-2), indicating that the spring maize field with straw returning on the Loess Plateau was a weak carbon sink.

  10. Spatiotemporal rain-fed wheat modeling using a land surface model and a crop stress index

    NASA Astrophysics Data System (ADS)

    Ghazanfari, Sadegh; Alizadeh, Amin; Faridhosseini, Alireza; Pande, Saket

    2013-04-01

    Rain-fed wheat yield estimation is an important issue in crop modeling. Regression and empirical equations are generally used to estimate wheat yields based on effective factors. These equations also need to be calibrated for each study area. Further, employing inaccurate inputs increases prediction uncertainty. Precipitation is the most important input for the rain-fed crops modeling and often interpolated data for areas without rain gauges is used. In this study, the outputs of two precipitation estimation models based on remotely sensed data, PERSIANN and TRMM, are used as alternatives to interpolated data. Results show that the precipitation estimation models outputs are more correlated with observed data than the interpolated precipitation data. Correlation coefficient at a meteorological station in Iran based on Kendall's test is 0.8 for PERSIANN while it is 0.4 and 0.5 for two interpolation methods, Inverse Distance Weighting and Kriging respectively. A simple evaporation/transpiration scheme (SETS), which is a distributed land surface model, has also been developed to estimate actual evaporation and transpiration. Finally a new crop stress index based on actual by potential transpiration (APT) is introduced to model crop yield by using SETS outputs at field scale. Results show that modeling crop yields based on APT, when SETS is forced by local field datasets at 10 sites, can estimate yields reasonably well when compared with other methods. The correlation coefficient with the observed yield data is at least 0.5 and the LSD (Least Significant Difference) test show no significant difference between measured and modeled yields at all sites. Our estimation method performs better than other methods in estimating yields based on the yields predicted by the other methods at the same sites.

  11. Comparison of winter wheat yield sensitivity to climate variables under irrigated and rain-fed conditions

    NASA Astrophysics Data System (ADS)

    Xiao, Dengpan; Shen, Yanjun; Zhang, He; Moiwo, Juana P.; Qi, Yongqing; Wang, Rende; Pei, Hongwei; Zhang, Yucui; Shen, Huitao

    2016-09-01

    Crop simulation models provide alternative, less time-consuming, and cost-effective means of determining the sensitivity of crop yield to climate change. In this study, two dynamic mechanistic models, CERES (Crop Environment Resource Synthesis) and APSIM (Agricultural Production Systems Simulator), were used to simulate the yield of wheat ( Triticum aestivum L.) under well irrigated (CFG) and rain-fed (YY) conditions in relation to different climate variables in the North China Plain (NCP). The study tested winter wheat yield sensitivity to different levels of temperature, radiation, precipitation, and atmospheric carbon dioxide (CO2) concentration under CFG and YY conditions at Luancheng Agro-ecosystem Experimental Stations in the NCP. The results from the CERES and APSIM wheat crop models were largely consistent and suggested that changes in climate variables influenced wheat grain yield in the NCP. There was also significant variation in the sensitivity of winter wheat yield to climate variables under different water (CFG and YY) conditions. While a temperature increase of 2°C was the threshold beyond which temperature negatively influenced wheat yield under CFG, a temperature rise exceeding 1°C decreased winter wheat grain yield under YY. A decrease in solar radiation decreased wheat grain yield under both CFG and YY conditions. Although the sensitivity of winter wheat yield to precipitation was small under the CFG, yield decreased significantly with decreasing precipitation under the rainfed YY treatment. The results also suggest that wheat yield under CFG linearly increased by ≈3.5% per 60 ppm (parts per million) increase in CO2 concentration from 380 to 560 ppm, and yield under YY increased linearly by ≈7.0% for the same increase in CO2 concentration.

  12. DENTAL LESIONS IN THE LOWLAND TAPIR (TAPIRUS TERRESTRIS).

    PubMed

    Tjørnelund, Karen B; Jonsson, Lena M; Kortegaard, Hanne; Arnbjerg, Jens; Nielsen, Søren S; Bertelsen, Mads F

    2015-06-01

    Dental ailments, mandibular swelling, and dentoalveolar abscesses are common in tapirs, but knowledge about prevalence or etiology of these lesions in the Tapiridae family in general, and in lowland tapirs (Tapirus terrestris) in particular, is scarce. A recent study identified resorptive lesions of unknown etiology as a common problem in the Malayan tapir (Tapirus indicus). In order to investigate the type and prevalence of dental lesions occurring in lowland tapirs, and to compare these with findings with the Malayan tapir, skulls and teeth from 46 deceased lowland tapirs were visually and radiographically examined. The specimens were divided into subpopulations according to age (juveniles, young adults, adults) and origin (free-range or captive). Dental lesions were identified in 24% (11/46) of the study population. The most common pathologic findings were complicated dental fractures with associated periapical reaction (15%) and periapical reactions of various degrees without associated detectable dental pathology (13%). All these lesions likely originated from dental trauma. As in Malayan tapirs, juveniles had significantly fewer lesions than adults. This study shows that dental lesions present frequent problems for lowland tapirs, occurring both in captive and in free-ranging individuals, and indicates that increasing age should be considered a risk factor for the development of these lesions. Notably, the predominant dental problems in lowland tapirs and Malayan tapirs are not the same.

  13. Methods and future directions for paleoclimatology in the Maya Lowlands

    NASA Astrophysics Data System (ADS)

    Douglas, Peter M. J.; Brenner, Mark; Curtis, Jason H.

    2016-03-01

    A growing body of paleoclimate data indicates that periods of severe drought affected the Maya Lowlands of southeastern Mexico and northern Central America, especially during the Terminal Classic period (ca. 800-950 CE), raising the possibility that climate change contributed to the widespread collapse of many Maya polities at that time. A broad range of paleoclimate proxy methods have been applied in the Maya Lowlands and the data derived from these methods are sometimes challenging for archeologists and other non-specialists to interpret. This paper reviews the principal methods used for paleoclimate inference in the region and the rationale for climate proxy interpretation to help researchers working in the Maya Lowlands make sense of paleoclimate datasets. In particular, we focus on analyses of speleothems and lake sediment cores. These two paleoclimate archives have been most widely applied in the Maya Lowlands and have the greatest potential to provide insights into climate change impacts on the ancient Maya. We discuss the development of chronologies for these climate archives, the proxies for past climate change found within them, and how these proxy variables are interpreted. Finally, we present strategies for improving our understanding of proxy paleoclimate data from the Maya Lowlands, including multi-proxy analyses, assessment of spatial variability in past climate change, combined analysis of climate models and proxy data, and the integration of paleoclimatology and archeology.

  14. Rice ( Oryza) hemoglobins

    PubMed Central

    Arredondo-Peter, Raúl; Moran, Jose F.; Sarath, Gautam

    2014-01-01

    Hemoglobins (Hbs) corresponding to non-symbiotic (nsHb) and truncated (tHb) Hbs have been identified in rice ( Oryza). This review discusses the major findings from the current studies on rice Hbs. At the molecular level, a family of the nshb genes, consisting of hb1, hb2, hb3, hb4 and hb5, and a single copy of the thb gene exist in Oryza sativa var. indica and O. sativa var. japonica, Hb transcripts coexist in rice organs and Hb polypeptides exist in rice embryonic and vegetative organs and in the cytoplasm of differentiating cells. At the structural level, the crystal structure of rice Hb1 has been elucidated, and the structures of the other rice Hbs have been modeled. Kinetic analysis indicated that rice Hb1 and 2, and possibly rice Hb3 and 4, exhibit a very high affinity for O 2, whereas rice Hb5 and tHb possibly exhibit a low to moderate affinity for O 2. Based on the accumulated information on the properties of rice Hbs and data from the analysis of other plant and non-plant Hbs, it is likely that Hbs play a variety of roles in rice organs, including O 2-transport, O 2-sensing, NO-scavenging and redox-signaling. From an evolutionary perspective, an outline for the evolution of rice Hbs is available. Rice nshb and thb genes vertically evolved through different lineages, rice nsHbs evolved into clade I and clade II lineages and rice nshbs and thbs evolved under the effect of neutral selection. This review also reveals lacunae in our ability to completely understand rice Hbs. Primary lacunae are the absence of experimental information about the precise functions of rice Hbs, the properties of modeled rice Hbs and the cis-elements and trans-acting factors that regulate the expression of rice hb genes, and the partial understanding of the evolution of rice Hbs. PMID:25653837

  15. Rice ( Oryza) hemoglobins.

    PubMed

    Arredondo-Peter, Raúl; Moran, Jose F; Sarath, Gautam

    2014-01-01

    Hemoglobins (Hbs) corresponding to non-symbiotic (nsHb) and truncated (tHb) Hbs have been identified in rice ( Oryza). This review discusses the major findings from the current studies on rice Hbs. At the molecular level, a family of the nshb genes, consisting of hb1, hb2, hb3, hb4 and hb5, and a single copy of the thb gene exist in Oryza sativa var. indica and O. sativa var. japonica, Hb transcripts coexist in rice organs and Hb polypeptides exist in rice embryonic and vegetative organs and in the cytoplasm of differentiating cells. At the structural level, the crystal structure of rice Hb1 has been elucidated, and the structures of the other rice Hbs have been modeled. Kinetic analysis indicated that rice Hb1 and 2, and possibly rice Hb3 and 4, exhibit a very high affinity for O 2, whereas rice Hb5 and tHb possibly exhibit a low to moderate affinity for O 2. Based on the accumulated information on the properties of rice Hbs and data from the analysis of other plant and non-plant Hbs, it is likely that Hbs play a variety of roles in rice organs, including O 2-transport, O 2-sensing, NO-scavenging and redox-signaling. From an evolutionary perspective, an outline for the evolution of rice Hbs is available. Rice nshb and thb genes vertically evolved through different lineages, rice nsHbs evolved into clade I and clade II lineages and rice nshbs and thbs evolved under the effect of neutral selection. This review also reveals lacunae in our ability to completely understand rice Hbs. Primary lacunae are the absence of experimental information about the precise functions of rice Hbs, the properties of modeled rice Hbs and the cis-elements and trans-acting factors that regulate the expression of rice hb genes, and the partial understanding of the evolution of rice Hbs.

  16. Drought yield index to select high yielding rice lines under different drought stress severities.

    PubMed

    Raman, Anitha; Verulkar, Satish; Mandal, Nimai; Variar, Mukund; Shukla, V; Dwivedi, J; Singh, B; Singh, O; Swain, Padmini; Mall, Ashutosh; Robin, S; Chandrababu, R; Jain, Abhinav; Ram, Tilatoo; Hittalmani, Shailaja; Haefele, Stephan; Piepho, Hans-Peter; Kumar, Arvind

    2012-12-01

    Drought is the most severe abiotic stress reducing rice yield in rainfed drought prone ecosystems. Variation in intensity and severity of drought from season to season and place to place requires cultivation of rice varieties with different level of drought tolerance in different areas. Multi environment evaluation of breeding lines helps breeder to identify appropriate genotypes for areas prone to similar level of drought stress. From a set of 129 advanced rice (Oryza sativa L.) breeding lines evaluated under rainfed drought-prone situations at three locations in eastern India from 2005 to 2007, a subset of 39 genotypes that were tested for two or more years was selected to develop a drought yield index (DYI) and mean yield index (MYI) based on yield under irrigated, moderate and severe reproductive-stage drought stress to help breeders select appropriate genotypes for different environments. ARB 8 and IR55419-04 recorded the highest drought yield index (DYI) and are identified as the best drought-tolerant lines. The proposed DYI provides a more effective assessment as it is calculated after accounting for a significant genotype x stress-level interaction across environments. For rainfed areas with variable frequency of drought occurrence, Mean yield index (MYI) along with deviation in performance of genotypes from currently cultivated popular varieties in all situations helps to select genotypes with a superior performance across irrigated, moderate and severe reproductive-stage drought situations. IR74371-70-1-1 and DGI 75 are the two genotypes identified to have shown a superior performance over IR64 and MTU1010 under all situations. For highly drought-prone areas, a combination of DYI with deviation in performance of genotypes under irrigated situations can enable breeders to select genotypes with no reduction in yield under favorable environments compared with currently cultivated varieties. For rainfed areas with variable frequency of drought stress, use of

  17. Hydroecological impacts of climate change modelled for a lowland UK wetland

    NASA Astrophysics Data System (ADS)

    House, Andrew; Acreman, Mike; Sorensen, James; Thompson, Julian

    2015-04-01

    Conservation management of wetlands often rests on modifying hydrological functions to establish or maintain desired flora and fauna. Hence the ability to predict the impacts of climate change is highly beneficial. Here, the physically based, distributed model MIKE SHE was used to simulate hydrology for the Lambourn Observatory at Boxford, UK. This comprises a 10 ha lowland riparian wetland protected for conservation, where the degree of variability in the peat, gravel and chalk geology has clouded hydrological understanding. Notably, a weathered layer on the chalk aquifer surface seals it from overlying deposits, yet is highly spatially heterogeneous. Long-term monitoring yielded observations of groundwater and surface water levels for model calibration and validation. Simulated results were consistent with observed data and reproduced the effects of seasonal fluctuations and in-channel macrophyte growth. The adjacent river and subsidiary channel were found to act as head boundaries, exerting a general control on water levels across the site. Discrete areas of groundwater upwellings caused raised water levels at distinct locations within the wetland. These were concurrent to regions where the weathered chalk layer is absent. To assess impacts of climate change, outputs from the UK Climate Projections 2009 ensemble of global climate models for the 2080s are used to obtain monthly percentage changes in climate variables. Changes in groundwater levels were taken from a regional model of the Chalk aquifer. Values of precipitation and evapotranspiration were seen to increase, whilst groundwater levels decreased, resulting in the greater dominance of precipitation. The discrete areas of groundwater upwelling were seen to diminish or disappear. Simulated water levels were linked to specific requirements of wetland plants using water table depth zone diagrams. Increasing depth of winter and summer groundwater levels leads to a loss of Glyceria maxima and Phragmites

  18. Genetics, Physiological Mechanisms and Breeding of Flood-Tolerant Rice (Oryza sativa L.).

    PubMed

    Singh, Anuradha; Septiningsih, Endang M; Balyan, Harendra S; Singh, Nagendra K; Rai, Vandna

    2017-02-01

    Flooding of rice fields is a serious problem in the river basins of South and South-East Asia where about 15 Mha of lowland rice cultivation is regularly affected. Flooding creates hypoxic conditions resulting in poor germination and seedling establishment. Flash flooding, where rice plants are completely submerged for 10-15 d during their vegetative stage, causes huge losses. Water stagnation for weeks to months also leads to substantial yield losses when large parts of rice aerial tissues are inundated. The low-yielding traditional varieties and landraces of rice adapted to these flooding conditions have been replaced by flood-sensitive high-yielding rice varieties. The 'FR13A' rice variety and the Submergence 1A (SUB1A) gene were identified for flash flooding and subsequently introgressed to high-yielding rice varieties. The challenge is to find superior alleles of the SUB1A gene, or even new genes that may confer greater tolerance to submergence. Similarly, genes have been identified in tolerant landraces of rice for their ability to survive by rapid stem elongation (SNORKEL1 and SNORKEL2) during deep-water flooding, and for anaerobic germination ability (TPP7). Research on rice genotypes and novel genes that are tolerant to prolonged water stagnation is in progress. These studies will greatly assist in devising more efficient and precise molecular breeding strategies for developing climate-resilient high-yielding rice varieties for flood-prone regions. Here we review the state of our knowledge of flooding tolerance in rice and its application in varietal improvement. © The Author 2017. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  19. Deforestation scenarios for the Bolivian lowlands.

    PubMed

    Tejada, Graciela; Dalla-Nora, Eloi; Cordoba, Diana; Lafortezza, Raffaele; Ovando, Alex; Assis, Talita; Aguiar, Ana Paula

    2016-01-01

    all Bolivian lowlands reaching 37,944,434 ha and leaves small forest patches in a few PAs. These deforestation scenarios are not meant to predict the future but to show how current and future decisions carried out by the neo-extractivist practices of MAS government could affect deforestation and carbon emission trends. In this perspective, recognizing land use systems as open and dynamic systems is a central challenge in designing efficient land use policies and managing a transition towards sustainable land use. Copyright © 2015 Elsevier Inc. All rights reserved.

  20. Water resources of the Southeast Lowlands, Missouri

    USGS Publications Warehouse

    Luckey, R.R.; Fuller, D.L.

    1985-01-01

    The Southeast Lowlands of Missouri occupies 4,000 square miles of prime agricultural land of the Coastal Plain in the extreme southeastern corner of Missouri. Even though this area receives about 4 feet of rainfall per year, there is a rapidly increasing demand for water for irrigation. The purpose of this study was to evaluate the water resources of this area with particular emphasis on the extent of irrigation and the potential of the groundwater system to support further irrigation development. The area is underlain by consolidated aquifers of Paleozoic age and unconsolidated aquifers of Mesozoic and Cenozoic age. The consolidated aquifers, although possessing the potential to yield large quantities of water, generally are not used throughout much of the area because they lie at considerable death and alternate supplies are readily available. The McNairy aquifer, which underlies about three-fourths of the area, ranges from 0 to 600 feet in thickness with the top lying from 0 to more than 2,200 feet below land surface. This system is attractive as a municipal water supply because of its large artesian head and the small iron and hardness concentrations of the water. Although this system is now used exclusively for municipal water supplies, the McNairy may become more important in the future as a heat source. The Wilcox Group (undivided), which underlies more than one-half of the area and almost always lies less than 300 feet below land surface, is as much as 1,400 feet thick. However, usually only the basal 250 to 500 feet of this group is used as an aquifer. This system, which in some areas is capable of yielding as much as 1,500 gallons per minute to properly constructed wells, is now primarily used for municipal supplies. The alluvial aquifer underlies most of the area and is locally capable of yielding more than 3,000 gallons per minute. This aquifer generally is 100 to 200 feet thick, but in several places more than 250 feet of alluvium has been reported

  1. Development and field performance of nitrogen use efficient rice lines for Africa.

    PubMed

    Selvaraj, Michael Gomez; Valencia, Milton Orlando; Ogawa, Satoshi; Lu, Yingzhi; Wu, Liying; Downs, Christopher; Skinner, Wayne; Lu, Zhongjin; Kridl, Jean C; Ishitani, Manabu; van Boxtel, Jos

    2016-11-27

    Nitrogen (N) fertilizers are a major input cost in rice production, and its excess application leads to major environmental pollution. Development of rice varieties with improved nitrogen use efficiency (NUE) is essential for sustainable agriculture. Here, we report the results of field evaluations of marker-free transgenic NERICA4 (New Rice for Africa 4) rice lines overexpressing barley alanine amino transferase (HvAlaAT) under the control of a rice stress-inducible promoter (pOsAnt1). Field evaluations over three growing seasons and two rice growing ecologies (lowland and upland) revealed that grain yield of pOsAnt1:HvAlaAT transgenic events was significantly higher than sibling nulls and wild-type controls under different N application rates. Our field results clearly demonstrated that this genetic modification can significantly increase the dry biomass and grain yield compared to controls under limited N supply. Increased yield in transgenic events was correlated with increased tiller and panicle number in the field, and evidence of early establishment of a vigorous root system in hydroponic growth. Our results suggest that expression of the HvAlaAT gene can improve NUE in rice without causing undesirable growth phenotypes. The NUE technology described in this article has the potential to significantly reduce the need for N fertilizer and simultaneously improve food security, augment farm economics and mitigate greenhouse gas emissions from the rice ecosystem.

  2. SNPs in stress-responsive rice genes: validation, genotyping, functional relevance and population structure

    PubMed Central

    2012-01-01

    Background Single nucleotide polymorphism (SNP) validation and large-scale genotyping are required to maximize the use of DNA sequence variation and determine the functional relevance of candidate genes for complex stress tolerance traits through genetic association in rice. We used the bead array platform-based Illumina GoldenGate assay to validate and genotype SNPs in a select set of stress-responsive genes to understand their functional relevance and study the population structure in rice. Results Of the 384 putative SNPs assayed, we successfully validated and genotyped 362 (94.3%). Of these 325 (84.6%) showed polymorphism among the 91 rice genotypes examined. Physical distribution, degree of allele sharing, admixtures and introgression, and amino acid replacement of SNPs in 263 abiotic and 62 biotic stress-responsive genes provided clues for identification and targeted mapping of trait-associated genomic regions. We assessed the functional and adaptive significance of validated SNPs in a set of contrasting drought tolerant upland and sensitive lowland rice genotypes by correlating their allelic variation with amino acid sequence alterations in catalytic domains and three-dimensional secondary protein structure encoded by stress-responsive genes. We found a strong genetic association among SNPs in the nine stress-responsive genes with upland and lowland ecological adaptation. Higher nucleotide diversity was observed in indica accessions compared with other rice sub-populations based on different population genetic parameters. The inferred ancestry of 16% among rice genotypes was derived from admixed populations with the maximum between upland aus and wild Oryza species. Conclusions SNPs validated in biotic and abiotic stress-responsive rice genes can be used in association analyses to identify candidate genes and develop functional markers for stress tolerance in rice. PMID:22921105

  3. Elastic Thickness Estimates for the Northern Lowlands of Mars

    NASA Astrophysics Data System (ADS)

    Hoogenboom, T.; Smrekar, S. E.

    2006-05-01

    The northern lowlands cover 1/3 of Mars' surface and are a fundamental part of the geologic evolution of Mars. We examine the admittance, (ratio of gravity to topography in the spectral domain), to better constrain the timing of northern lowlands formation. Prior to this study there have been no successful estimates of elastic thickness (Te) in the lowlands (with the exception of Utopia) due to low topographic signal. We use a Cartesian multitaper approach (that has been successful for topographically eroded regions on Earth) to estimate Te for 4 lowland regions. These regions are well resolved in the gravity data, display well constrained lithospheric parameters, and topographic power spectra similar to many highlands regions. We use the latest spherical harmonic gravity field (MGS95J), carried out to degree and order 95. The field is determined globally to degree 70 (~305km), where the noise of the unconstrained solution equals the signal. Spherical harmonic coefficients for the topography were created in the same reference as the gravity. We compare the observed admittance with those predicted from lithospheric flexure models. On the basis of these comparisons, we estimate the Te required to support the observed topographic load since the time of loading. Top and bottom loading models are used to derive Te and crustal thickness or apparent depth of compensation. All 4 regions are best fit by a bottom-loading model. We obtain best fit Te estimates between 10-25km with an acceptable error range of 0-45km. These small estimates are similar to previous studies of the southern highlands and are consistent with formation in the Noachian when heat flow was high. The consistency in Te estimates between the Noachian highlands and lowlands basement suggests that both regions of the crust formed within a short time. The paucity of crustal magnetization in the lowlands is thus more likely a result of demagnetization than formation following shutdown of the dynamo. Most

  4. Origin of northern lowland plains: Constraints from boundary morphology

    NASA Astrophysics Data System (ADS)

    Parker, Timothy J.; Saunders, R. Stephen

    The origin of the surface units of the northern lowland plains of Mars, about one third of the planet's surface, remains unclear after 20 years of analysis of spacecraft data. Hypotheses were put forward to explain the morphologies. The chief problem with constraining models of plains formation is that characterizing plains surface-forming processes is dependent upon the identification of distinctive landforms within the plains. The most commonly cited examples of distinctive morphologies found within the northern lowlands include: wrinkle ridges; small domes; giant polygons; and curvilinear ridges and ground undulations. To further constrain the processes involved, a careful analysis of boundary morphology is being conducted.

  5. Agro-ecological variations of sheath rot disease of rice caused by Sarocladium oryzae and DNA fingerprinting of the pathogen's population structure.

    PubMed

    Tajul Islam Chowdhury, M; Salim Mian, M; Taher Mia, M A; Rafii, M Y; Latif, M A

    2015-12-28

    To examine the impact of regional and seasonal variations on the incidence and severity of sheath rot, a major seed-borne disease of rice caused by Sarocladium oryzae, data on incidence and severity were collected from 27 selected fields in the Gazipur, Rangpur, Bogra, Chittagong, Comilla, Gopalgonj, Jessore, Manikgonj, and Bhola districts of Bangladesh in rain-fed and irrigated conditions. Cultural variability of 29 pathogen isolates obtained from 8 different locations was studied on potato dextrose agar (PDA) and genetic variability was determined by DNA fingerprinting using variable number tandem repeat-polymerase chain reaction markers. Overall, disease incidence and severity were higher in irrigated rice. Disease incidence and severity were highest in the Bhola district in rain-fed rice and lowest in irrigated rice. Mycelial growth of 29 representative isolates was found to vary on PDA and the isolates were divided into 6 groups. The range of the overall size of conidia of the selected isolates was 2.40-7.20 x 1.20-2.40 μm. Analysis of the DNA fingerprint types of the 29 isolates of S. oryzae, obtained from the amplification reactions, revealed 10 fingerprinting types (FPTs) that were 80% similar. FPT-1 was the largest group and included 13 isolates (44.8%), while FPT-2 was the third largest group and included 3 isolates. Each of FPT-3, 4, 5, and 6 included only 1 isolate. We observed no relationship between cultural and genetic groupings.

  6. Identification of greenhouse gas hot-spots and predicting district-wise GHG Intensities in rice based crop rotations in India using DNDC model

    NASA Astrophysics Data System (ADS)

    Yeluripati, J. B.; Frolking, S. E.; Li, C.; Nayak, D. R.; Adhya, T. K.

    2014-12-01

    Indian scientific research on rice cultivation has been targeted primarily at enhancing crop productivity for the wide range of soil and climate conditions across India. With the understanding that rice paddies are major source of atmospheric CH4 and N2O, there is a need for careful evaluation of the source strength of this ecosystem, and the influence of soil, water and crop management practices on both CH4 and N2O fluxes. A major challenge in meeting this objective lies in reducing the large uncertainties associated with regional and global level estimates of GHG emissions. Process-based biogeochemical models like DNDC (Denitrification and Decomposition model) can provide important insights into how agricultural management of rice paddies influences water resources, yields and greenhouse gas emissions. To quantify the CH4 and N2­O emissions from rice based crop rotations of India, DNDC model was modified, calibrated and evaluated at different sites across India. The observed N uptake, yields, CH4 and N2O emissions were in agreement with the values predicted by the model. To drive the model across India, a unique database was prepared combining soil/climate/landuse and management information. By linking the spatial database to DNDC, CH4 and N2O emissions from Indian rice based crop rotations for the rice growing season in the year 2000 were simulated on day-by-day basis. CH4 and N2O emissions from rice paddies in India from rice based-growing season were estimated to be 3.8 and 0.1 - 0.08 Tg (1 Tg = 1012 gm). Of the total CH4 emissions 30.6% (1.2 Tg) is emitted from single irrigated rice. 30.0% (1.1 Tg) and 14.46%(0.56 Tg) of total CH4 is emitted from double rice and single rainfed rice cropping system. 32.9% (33.16 Gg) of the total N2O emissions is emitted by upland rice followed by Single rainfed rice cropping system which emits about 19.9%(20.06 Gg) of total N2O . This paper presents a framework on GIS databases and a process-based biogeochemical model for

  7. Dynamics of Soil Heat Flux in Lowland Area: Estimating the Soil Thermal Conductivy

    NASA Astrophysics Data System (ADS)

    Zimmer, T.; Silveira, M. V.; Roberti, D. R.

    2013-05-01

    In this work, it is shown soil thermal conductivity estimates in a flooded irrigated rice culture located at the Paraíso do Sul city for two distinct periods. The thermal conductivity is higher when the heat storage is higher and the soil surface temperature is lower. The soil thermal conductivity is also dependant on the soil texture, porosity and moisture. Therefore, it varies from soil to soil and in the same soil, depending on its soil moisture. For approximately 80% of its growing season, lowland flooded irrigated rice ecosystems stay under a 5 - 10 cm water layer. It affects the partitioning of the energy and water balance components. Furthermore this planting technique differs substantially from any other upland non-irrigated or irrigated crop ecosystems where the majority of observational studies have been conducted. In the present work, the dynamic of soil heat flux (G) is analyzed and the soil thermal conductivity (Ks) is estimated using experimental data form soil heat flux and soil temperature in a rice paddy farm in a subtropical location in Southern Brazil. In this region, rice grows once a year at river lowlands and wetlands while the ground is kept bare during the remaining of the year. The soil type is Planossolo Hidromórfico Distrófico, characterized as a mix between sandy and clay soil. The soil heat flux (G) was experimentally estimated with the sensor Hukseflux (HFP01SC-L) at 7 cm bellow the soil surface. The soil temperature at 5 cm and 10 cm was experimentally estimated using the sensor STP01. The experimental soil heat flux was compared with estimated soil heat flux by two forms: (1) using a know Ks from literature for this type of soil in saturated conditions (Ks=1.58); (2) using Ks estimated using the inversion of the equation Qg=-ks* ((T10-T5)/ (Z2-Z1)), where T10 and T5 are the temperature in 10 and 5 cm above the soil and Z2-Z1 is the difference between the positions in temperature measurement. The study period for estimating the Ks

  8. Reduced ABA Accumulation in the Root System is Caused by ABA Exudation in Upland Rice (Oryza sativa L. var. Gaoshan1) and this Enhanced Drought Adaptation.

    PubMed

    Shi, Lu; Guo, Miaomiao; Ye, Nenghui; Liu, Yinggao; Liu, Rui; Xia, Yiji; Cui, Suxia; Zhang, Jianhua

    2015-05-01

    Lowland rice (Nipponbare) and upland rice (Gaoshan 1) that are comparable under normal and moderate drought conditions showed dramatic differences in severe drought conditions, both naturally occurring long-term drought and simulated rapid water deficits. We focused on their root response and found that enhanced tolerance of upland rice to severe drought conditions was mainly due to the lower level of ABA in its roots than in those of the lowland rice. We first excluded the effect of ABA biosynthesis and catabolism on root-accumulated ABA levels in both types of rice by monitoring the expression of four OsNCED genes and two OsABA8ox genes. Next, we excluded the impact of the aerial parts on roots by suppressing leaf-biosynthesized ABA with fluridone and NDGA (nordihydroguaiaretic acid), and measuring the ABA level in detached roots. Instead, we proved that upland rice had the ability to export considerably more root-sourced ABA than lowland rice under severe drought, which improved ABA-dependent drought adaptation. The investigation of apoplastic pH in root cells and root anatomy showed that ABA leakage in the root system of upland rice was related to high apoplastic pH and the absence of Casparian bands in the sclerenchyma layer. Finally, taking some genes as examples, we predicted that different ABA levels in rice roots stimulated distinct ABA perception and signaling cascades, which influenced its response to water stress. © The Author 2015. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  9. Daily extreme precipitation indices and their impacts on rice yield—A case study over the tropical island in China

    NASA Astrophysics Data System (ADS)

    Li, Mao-Fen; Luo, Wei; Li, Hailiang; Liu, Enping; Li, Yuping

    2017-03-01

    Frequent occurrences of extreme precipitation events have significant impacts on agricultural production. Tropical agriculture has been playing an important role in national economy in China. A precise understanding of variability in extreme precipitation indices and their impacts on crop yields are of great value for farmers and policy makers at county level, particularly in tropical China where almost all agriculture is rainfed. This research has studied observed trends in extreme precipitation indices (a total of 10) during 1988-2013 over Hainan island, tropical China. Mann-Kendall nonparametric test was adopted for trend detection and the results showed that most of precipitation indices showed increasing trend. Since rice is the most important staple food in Hainan island, the impacts of extreme precipitation indices on rice yields were also analyzed through simple correlations. In general, the rainy days and rain intensity in late rice growing season showed increasing trend over Hainan island. The rice yield presented ninth-degree polynomial technological trend at all stations and increasing trend for early rice yield. Late rice yield showed a decreasing trend in some parts of Hainan island. Spearman rank correlation coefficient indicated that the correlation was more pronounced between extreme precipitation indices and yields at Haikou site for early rice, and Haikou, Sanya, and Qionghai stations for late rice, respectively. Further results also indicated that there were statistically significant positive trends of R10 and R20 (number of days with precipitation ≥10 mm and precipitation ≥20 mm, respectively) from July to November at Haikou (located in north of Hainan island), and this positive trend may be a disadvantage for late rice yield. The cut-off value of extreme precipitation indices and its correlation with rice yield anomaly indices for Hainan island provided a foundation for vulnerability assessment as well as a contribution to set up

  10. Global rain-fed, irrigated, and paddy croplands: A new high resolution map derived from remote sensing, crop inventories and climate data

    NASA Astrophysics Data System (ADS)

    Salmon, J. Meghan; Friedl, Mark A.; Frolking, Steve; Wisser, Dominik; Douglas, Ellen M.

    2015-06-01

    Irrigation accounts for 70% of global water use by humans and 33-40% of global food production comes from irrigated croplands. Accurate and timely information related to global irrigation is therefore needed to manage increasingly scarce water resources and to improve food security in the face of yield gaps, climate change and extreme events such as droughts, floods, and heat waves. Unfortunately, this information is not available for many regions of the world. This study aims to improve characterization of global rain-fed, irrigated and paddy croplands by integrating information from national and sub-national surveys, remote sensing, and gridded climate data sets. To achieve this goal, we used supervised classification of remote sensing, climate, and agricultural inventory data to generate a global map of irrigated, rain-fed, and paddy croplands. We estimate that 314 million hectares (Mha) worldwide were irrigated circa 2005. This includes 66 Mha of irrigated paddy cropland and 249 Mha of irrigated non-paddy cropland. Additionally, we estimate that 1047 Mha of cropland are managed under rain-fed conditions, including 63 Mha of rain-fed paddy cropland and 985 Mha of rain-fed non-paddy cropland. More generally, our results show that global mapping of irrigated, rain-fed, and paddy croplands is possible by combining information from multiple data sources. However, regions with rapidly changing irrigation or complex mixtures of irrigated and non-irrigated crops present significant challenges and require more and better data to support high quality mapping of irrigation.

  11. A 2,000-year reconstruction of the rain-fed maize agricultural niche in the US Southwest.

    PubMed

    Bocinsky, R Kyle; Kohler, Timothy A

    2014-12-04

    Humans experience, adapt to and influence climate at local scales. Paleoclimate research, however, tends to focus on continental, hemispheric or global scales, making it difficult for archaeologists and paleoecologists to study local effects. Here we introduce a method for high-frequency, local climate-field reconstruction from tree-rings. We reconstruct the rain-fed maize agricultural niche in two regions of the southwestern United States with dense populations of prehispanic farmers. Niche size and stability are highly variable within and between the regions. Prehispanic rain-fed maize farmers tended to live in agricultural refugia--areas most reliably in the niche. The timing and trajectory of the famous thirteenth century Pueblo migration can be understood in terms of relative niche size and stability. Local reconstructions like these illuminate the spectrum of strategies past humans used to adapt to climate change by recasting climate into the distributions of resources on which they depended.

  12. A 2,000-year reconstruction of the rain-fed maize agricultural niche in the US Southwest

    NASA Astrophysics Data System (ADS)

    Bocinsky, R. Kyle; Kohler, Timothy A.

    2014-12-01

    Humans experience, adapt to and influence climate at local scales. Paleoclimate research, however, tends to focus on continental, hemispheric or global scales, making it difficult for archaeologists and paleoecologists to study local effects. Here we introduce a method for high-frequency, local climate-field reconstruction from tree-rings. We reconstruct the rain-fed maize agricultural niche in two regions of the southwestern United States with dense populations of prehispanic farmers. Niche size and stability are highly variable within and between the regions. Prehispanic rain-fed maize farmers tended to live in agricultural refugia—areas most reliably in the niche. The timing and trajectory of the famous thirteenth century Pueblo migration can be understood in terms of relative niche size and stability. Local reconstructions like these illuminate the spectrum of strategies past humans used to adapt to climate change by recasting climate into the distributions of resources on which they depended.

  13. Rainfall and crop modeling-based water stress assessment for rainfed maize cultivation in peninsular India

    NASA Astrophysics Data System (ADS)

    Manivasagam, V. S.; Nagarajan, R.

    2017-03-01

    Water stress due to uneven rainfall distribution causes a significant impact on the agricultural production of monsoon-dependent peninsular India. In the present study, water stress assessment for rainfed maize crop is carried out for kharif (June-October) and rabi (October-February) cropping seasons which coincide with two major Indian monsoons. Rainfall analysis (1976-2010) shows that the kharif season receives sufficient weekly rainfall (28 ± 32 mm) during 26th-39th standard meteorological weeks (SMWs) from southwest monsoon, whereas the rabi season experiences a major portion of its weekly rainfall due to northeast monsoon between the 42nd and 51st SMW (31 ± 42 mm). The later weeks experience minimal rainfall (5.5 ± 15 mm) and thus expose the late sown maize crops to a severe water stress during its maturity stage. Wet and dry spell analyses reveal a substantial increase in the rainfall intensity over the last few decades. However, the distribution of rainfall shows a striking decrease in the number of wet spells, with prolonged dry spells in both seasons. Weekly rainfall classification shows that the flowering and maturity stages of kharif maize (33rd-39th SMWs) can suffer around 30-40% of the total water stress. In the case of rabi maize, the analysis reveals that a shift in the sowing time from the existing 42nd SMW (16-22 October) to the 40th SMW (1-7 October) can avoid terminal water stress. Further, AquaCrop modeling results show that one or two minimal irrigations during the flowering and maturity stages (33rd-39th SMWs) of kharif maize positively avoid the mild water stress exposure. Similarly, rabi maize requires an additional two or three lifesaving irrigations during its flowering and maturity stages (48th-53rd SMWs) to improve productivity. Effective crop planning with appropriate sowing time, short duration crop, and high yielding drought-resistant varieties will allow for better utilization of the monsoon rain, thus reducing water stress with

  14. Comparing N2O emissions at varying N rates from irrigated and rainfed corn in the US Midwest

    NASA Astrophysics Data System (ADS)

    Millar, N.; Kahmark, K.; Basso, B.; Robertson, G. P.

    2011-12-01

    Global N2O emissions from agriculture are estimated to be ~2.8 Pg CO2e yr-1 accounting for 60% of total anthropogenic emissions. N2O is the largest contributor to the GHG burden of cropping systems in the US, with annual estimated emissions of ~0.5 Tg primarily due to N fertilizer inputs and other soil management activities. Currently 23 million acres of corn, soybean and wheat are irrigated annually in the US with increased N2O emissions due to the practice likely under-reported in GHG inventories. Here we compare N2O emissions and yield from irrigated and rainfed corn at varying N rates between 0 and 246 kg N ha-1 from the Kellogg Biological Station in SW Michigan. Initial results show that N2O emissions increase with increasing N rate and are significantly higher from irrigated corn compared to rainfed corn at the same N rate. At increasing N rates daily emissions following an irrigation event were between 2.4 - 77.5 g N2O-N ha-1 from irrigated corn and 1.6 - 13.0 g N2O-N ha-1 from rainfed corn. Emissions data from automated and static chambers will be presented and trade-offs between N2O emissions, N fertilizer rate, crop yield and irrigation practice will be evaluated from an environmental and economic standpoint.

  15. Long-term increase in diffuse groundwater recharge following expansion of rainfed cultivation in the Sahel, West Africa

    NASA Astrophysics Data System (ADS)

    Ibrahim, Maïmouna; Favreau, Guillaume; Scanlon, Bridget R.; Seidel, Jean Luc; Le Coz, Mathieu; Demarty, Jérôme; Cappelaere, Bernard

    2014-09-01

    Rapid population growth in sub-Saharan West Africa and related cropland expansion were shown in some places to have increased focused recharge through ponds, raising the water table. To estimate changes in diffuse recharge, the water content and matric potential were monitored during 2009 and 2010, and modeling was performed using the Hydrus-1D code for two field sites in southwest Niger: (1) fallow land and (2) rainfed millet cropland. Monitoring results of the upper 10 m showed increased water content and matric potential to greater depth under rainfed cropland (>2.5 m) than under fallow land (≤1.0 m). Model simulations indicate that conversion from fallow land to rainfed cropland (1) increases vadose-zone water storage and (2) should increase drainage flux (˜25 mm year-1) at 10-m depth after a 30-60 year lag. Therefore, observed regional increases in groundwater storage may increasingly result from diffuse recharge, which could compensate, at least in part, groundwater withdrawal due to observed expansion in irrigated surfaces; and hence, contribute to mitigate food crises in the Sahel.

  16. Constructed wetland attenuation of nitrogen exported in subsurface drainage from irrigated and rain-fed dairy pastures.

    PubMed

    Tanner, C C; Nguyen, M L; Sukias, J P S

    2005-01-01

    Nitrogen removal performance is reported for constructed wetlands treating subsurface drainage from irrigated and rain-fed dairy pastures in North Island, New Zealand. Flow-proportional sampling of inflow and outflow concentrations were combined with continuous flow records to calculate mass balances for the wetlands. Drainage flows from the irrigated catchment were 2.5-4 fold higher and N exports up to 5 fold higher per unit area than for the rain-fed catchment. Hydraulic and associated N loadings to the wetlands were highly pulsed, associated with rainfall, soil water status, and irrigation events. Transient pulses of organic nitrogen were an important form of N loss from the rain-fed landscape in the first year, and were very effectively removed in the wetland (> 90%). Median nitrate concentrations of approximately 10 g m(-3) in the drainage inflows were reduced by 15-67% during passage through the wetlands and annual nitrate-N loads by 16-61% (38-31 7 g N m(-2)y(-1)). Generation in the wetlands of net ammoniacal-N and organic-N (irrigated site) partially negated reduction in nitrate-N loads. The results show that constructed wetlands comprising 1-2% of catchment area can provide moderate reductions in TN export via pastoral drainage, but performance is markedly influenced by variations in seasonal loading and establishment/maturation factors.

  17. Thermal and visible remote sensing for estimation of evapotranspiration of rainfed agrosystems and its impact on groundwater in SE Australia

    NASA Astrophysics Data System (ADS)

    Roohi, Rakhshan; Webb, John A.

    2016-05-01

    Rainfed agrosystems are important components of the world's food production system and account for 65-95% of total agriculture. In contrast to irrigated production systems, relatively little attention has been paid to understanding the hydrological interactions between the components of rainfed agrosystems and their impact on water resources, especially groundwater. A new model, the Surface Energy Balance Algorithm for Rainfed Agriculture (SEBARA), has been developed to estimate the spatial pattern of evapotranspiration in these agrosystems using satellite images (thermal, infrared and visible spectra). The model was calibrated for two competing land uses (Eucalyptus globules tree plantations and pastures) in adjacent catchments in western Victoria, southeastern Australia. Using measurements from a flux tower in the pasture catchment and adjusted sapflow measurements in the plantation catchment, an estimation accuracy of 95% was achieved. The tree plantations had higher available net radiation, lower soil heat flux and higher latent heat flux, resulting in 15-20% higher evapotranspirative demand than the pasture, depending upon the age and canopy of plantations. The evapotranspiration rate of plantations declines where groundwater depth is >12m or where shallow groundwater is saline. The shallow root system of the pasture means that it relies solely on soil moisture to meet its water requirements and thus has lower evapotranspiration, which varies according to the pasture species.

  18. Surgical extractions for periodontal disease in a Western Lowland gorilla.

    PubMed

    Huff, John F

    2010-01-01

    This case report describes surgical exraction of multiple premolar and molar teeth in a Western Lowland gorilla. Postoperative photographs and radiographs indicated complete healing of the extraction sites. This case report includes a review of gorilla dental anatomy, oral disease in primates, pathogenesis of periodontal disease, predisposing factors to periodontal disease, and principles of surgical tooth extraction.

  19. Hyperspectral remote sensing of canopy biodiversity in Hawaiian lowland rainforests

    Treesearch

    Kimberly M. Carlson; Gregory P. Asner; R. Flint Hughes; Rebecca Ostertag; Roberta E. Martin

    2007-01-01

    Mapping biological diversity is a high priority for conservation research, management and policy development, but few studies have provided diversity data at high spatial resolution from remote sensing. We used airborne imaging spectroscopy to map woody vascular plant species richness in lowland tropical forest ecosystems in Hawaii. Hyperspectral signatures spanning...

  20. Retroperitoneal abscesses in two western lowland gorillas (Gorilla gorilla gorilla).

    PubMed

    Hahn, Alicia; D'Agostino, Jennifer; Cole, Gretchen A; Raines, Jan

    2014-03-01

    This report describes two cases of retroperitoneal abscesses in female western lowland gorillas (Gorilla gorilla gorilla). Clinical symptoms included perivulvar discharge, lameness, hindlimb paresis, and general malaise. Retroperitoneal abscesses should be considered as part of a complete differential list in female gorillas with similar clinical signs.

  1. An Indian Federation in Lowland Ecuador. IWGIA Document 28.

    ERIC Educational Resources Information Center

    Salazar, Ernesto

    Official involvement of the Ecuadorian government with colonization of the southern lowlands, lands traditionally belonging to the Shuar Indians, began in the early 60's when the CREA (Centro de Reconversion Economica del Azuay) was created to provide assistance to white settlers. Until that time, the Shuar lands had been dominated by the Salesian…

  2. Drought in an invaded Hawaiian lowland wet forest

    Treesearch

    Jené Michaud; Susan Cordell; T. Colleen Cole; Rebecca Ostertag

    2015-01-01

    In this study we examined historic drought frequency and hydrologic effects of removing invasive plants from one of the few remaining Hawaiian wet lowland forests, near Hilo, Hawai‘i. We developed a conceptual and statistical model of Hilo droughts using historic rainfall and pan evaporation data and discovered that episodes of low soil moisture were most likely from...

  3. Lowland riparian herpetofaunas: the San Pedro River in southeastern Arizona

    Treesearch

    Philip C. Rosen

    2005-01-01

    Previous work has shown that southeastern Arizona has a characteristic, high diversity lowland riparian herpetofauna with 62-68 or more species along major stream corridors, and 46-54 species in shorter reaches within single biomes, based on intensive fieldwork and museum record surveys. The San Pedro River supports this characteristic herpetofauna, at least some of...

  4. Methane emission from Indonesian rice fields with special references to the effects of yearly and seasonal variations, rice variety, soil type and water management

    NASA Astrophysics Data System (ADS)

    Lumbanraja, Jamalam; Ghani Nugroho, Sutopo; Niswati, Ainin; Sabe Ardjasa, Wayan; Subadiyasa, Netera; Arya, Nyoman; Haraguchi, Hiroki; Kimura, Makoto

    1998-10-01

    Total amounts of CH4 emission from a Sumatra rice field were in the ranges 29·5-48·2 and 43·0-64·6 g CH4 m-2 season-1 for the plots with chemical fertilizer (CF-plot) and those with rice straw application (RS-plot), respectively. Nearly the same amounts of CH4 were emitted in the first and second half of the growth period, irrespective of rice straw application. The increase in the amounts of CH4 emission by rice straw application were from 1·3 to 1·6 times. There was no significant difference in the mean CH4 emission rates between rainy and dry seasons. Rain-fed conditions decreased the CH4 emission by 27-37% compared with continuously flooded conditions. Total amounts of CH4 emission from a rice field growing eight popular modern rice varieties in Indonesia were in the ranges 32·6-41·7 and 51·3-64·6 g CH4 m-2 season-1 for CF- and RS-plots, respectively. Total amounts of CH4 emission from four Sumatra rice fields with different soil types (a Typic Paleudult, a Typic Sulfaquent, a Typic Tropohumult and a Typic Tropopsament) were in the range 22·1 (a Typic Sulfaquent) to 53·4 (a Typic Tropohumult) g CH4 m-2 season-1rice fields with soils of volcanic ash origin were very low; 3·5-7·7 and 5·3-14·3 g CHrice fields showed the specific productivity of grain production, and CHrice fields of volcanic ash origin to 83 and 121 g CHrice field for CF- and RS-plots, respectively. Water management was also an important factor in decreasing the CH

  5. Influence of nitrogen and sulfur fertilization on quality of canola (Brassica napus L.) under rainfed conditions*

    PubMed Central

    Ahmad, G.; Jan, A.; Arif, M.; Jan, M.T.; Khattak, R.A.

    2007-01-01

    Field experiments were conducted at Cereal Crops Research Institute, Pirsabak, Nowshera, Pakistan, during winter 2003~2004 and 2004~2005 to evaluate the effect of nitrogen and sulfur levels and methods of nitrogen application on canola (Brassica napus L. cv. Bulbul-98) under rainfed conditions. Four levels of S (0, 10, 20, and 30 kg/ha) and three levels of N (40, 60, and 80 kg/ha) and a control treatment with both nutrients at zero level were included in the experiments. Sulfur levels were applied at sowing while N levels were applied by three methods (100% soil application, 90% soil+10% foliar application, and 80% soil +20% foliar application). The experiments were laid out in randomized complete block (RCB) design having four replications. Oil content increased significantly up to 20 kg S/ha but further increase in S level did not enhance oil content. Glucosinolate content increased from 13.6 to 24.6 μmol/g as S rate was increased from 0 to 30 kg/ha. Protein content increased from 22.4% to 23.2% as S rate was increased from 0 to 20 kg/ha. Oil content responded negatively to the increasing N levels. The highest N level resulted in the highest values for protein (23.5%) and glucosinolate (19.9 μmol/g) contents. Methods of N application had no significant impact on any parameters under study. PMID:17910116

  6. Making the best of climatic variability: options for upgrading rainfed farming in water scarce regions.

    PubMed

    Rockström, J

    2004-01-01

    Coping with climatic variability for livelihood security is part of everyday life for rural communities in semi-arid and dry sub-humid savannas. Water scarcity caused by rainfall fluctuations is common, causing meteorological droughts and dry spells. However, this paper indicates, based on experiences in sub-Saharan Africa and India, that the social impact on rural societies of climatically induced droughts is exaggerated. Instead, water scarcity causing food deficits is more often caused by management induced droughts and dry spells. A conceptual framework to distinguish between manageable and unmanageable droughts is presented. It is suggested that climatic droughts require focus on social resilience building instead of land and water resource management. Focus is then set on the manageable part of climatic variability, namely the almost annual occurrence of dry spells, short 2-4 week periods of no rainfall, affecting farmer yields. On-farm experiences in savannas of sub-Saharan Africa of water harvesting systems for dry spell mitigation are presented. It is shown that bridging dry spells combined with soil fertility management can double and even triple on-farm yield levels. Combined with innovative systems to ensure maximum plant water availability and water uptake capacity, through adoption of soil fertility improvement and conservation tillage systems, there is a clear opportunity to upgrade rainfed farming systems in vulnerable savanna environments, through appropriate local management of climatic variability.

  7. Canopy management in rainfed vineyards (cv. Tempranillo) for optimising water use and enhancing wine quality.

    PubMed

    Pascual, Miquel; Romero, María-Paz; Rufat, Josep; Villar, Josep M

    2015-12-01

    Rainfed viticulture, mainly in semi-arid environments, is limited by environmental variability, particularly precipitation and its seasonal distribution, and soil water availability, thus ultimately determining the final quality of grape and wine. Studies on the feasibility of practices such as canopy management to adapt plant growth and yield to soil water availability open up possibilities to preserve wine quality and reinforce the characteristics of the terroir. Principal components analysis was used to identify the relationships between a large set of variables, including soil, plant, canopy management, and wine characteristics. Canopy management was found to have a predominant influence on plant response to soil water by modifying plant water status, changing the amino acid profile in berries and, concomitantly, altering the sensorial attributes of the wine obtained. Grapevine canopy management strategies, such as reiterate shoot trimming to restrict growth during early phases, are effective in adapting plant response to soil water availability. Such strategies affect berry and wine quality, mainly the amino acid profile and sensorial attributes of the wine, without changing yield or grape harvest quality control parameters. Also, in such conditions, nitrogen does not make a significant contribution to grapevine growth or yield or to grape quality. © 2015 Society of Chemical Industry.

  8. Rice Production and Marketing.

    ERIC Educational Resources Information Center

    Briers, Gary; Lee, Jasper S.

    This guide contains lesson plans for use in secondary programs of agricultural education in geographical areas in which rice is produced. Six units and 13 problem areas are organized into teaching plans that cover the broad nature of rice production. The six units are: (1) determining the importance and history of rice production; (2) determining…

  9. From Early Domesticated Rice of the Middle Yangtze Basin to Millet, Rice and Wheat Agriculture: Archaeobotanical Macro-Remains from Baligang, Nanyang Basin, Central China (6700-500 BC).

    PubMed

    Deng, Zhenhua; Qin, Ling; Gao, Yu; Weisskopf, Alison Ruth; Zhang, Chi; Fuller, Dorian Q

    2015-01-01

    Baligang is a Neolithic site on a northern tributary of the middle Yangtze and provides a long archaeobotanical sequence from the Seventh Millennium BC upto the First Millennium BC. It provides evidence for developments in rice and millet agriculture influenced by shifting cultural affiliation with the north (Yangshao and Longshan) and south (Qujialing and Shijiahe) between 4300 and 1800 BC. This paper reports on plant macro-remains (seeds), from systematic flotation of 123 samples (1700 litres), producing more than 10,000 identifiable remains. The earliest Pre-Yangshao occupation of the sites provide evidence for cultivation of rice (Oryza sativa) between 6300-6700 BC. This rice appears already domesticated in on the basis of a dominance of non-shattering spikelet bases. However, in terms of grain size changes has not yet finished, as grains are still thinner than more recent domesaticated rice and are closer in grain shape to wild rices. This early rice was cultivated alongside collection of wild staple foods, especially acorns (Quercus/Lithicarpus sensu lato). In later periods the sites has evidence for mixed farming of both rice and millets (Setaria italica and Panicum miliaceum). Soybean appears on the site in the Shijiahe period (ca.2500 BC) and wheat (Triticum cf. aestivum) in the Late Longshan levels (2200-1800 BC). Weed flora suggests an intensification of rice agriculture over time with increasing evidence of wetland weeds. We interpret these data as indicating early opportunistic cultivation of alluvial floodplains and some rainfed rice, developing into more systematic and probably irrigated cultivation starting in the Yangshao period, which intensified in the Qujialing and Shijiahe period, before a shift back to an emphasis on millets with the Late Longshan cultural influence from the north.

  10. From Early Domesticated Rice of the Middle Yangtze Basin to Millet, Rice and Wheat Agriculture: Archaeobotanical Macro-Remains from Baligang, Nanyang Basin, Central China (6700–500 BC)

    PubMed Central

    Deng, Zhenhua; Qin, Ling; Gao, Yu; Weisskopf, Alison Ruth; Zhang, Chi; Fuller, Dorian Q.

    2015-01-01

    Baligang is a Neolithic site on a northern tributary of the middle Yangtze and provides a long archaeobotanical sequence from the Seventh Millennium BC upto the First Millennium BC. It provides evidence for developments in rice and millet agriculture influenced by shifting cultural affiliation with the north (Yangshao and Longshan) and south (Qujialing and Shijiahe) between 4300 and 1800 BC. This paper reports on plant macro-remains (seeds), from systematic flotation of 123 samples (1700 litres), producing more than 10,000 identifiable remains. The earliest Pre-Yangshao occupation of the sites provide evidence for cultivation of rice (Oryza sativa) between 6300–6700 BC. This rice appears already domesticated in on the basis of a dominance of non-shattering spikelet bases. However, in terms of grain size changes has not yet finished, as grains are still thinner than more recent domesaticated rice and are closer in grain shape to wild rices. This early rice was cultivated alongside collection of wild staple foods, especially acorns (Quercus/Lithicarpus sensu lato). In later periods the sites has evidence for mixed farming of both rice and millets (Setaria italica and Panicum miliaceum). Soybean appears on the site in the Shijiahe period (ca.2500 BC) and wheat (Triticum cf. aestivum) in the Late Longshan levels (2200–1800 BC). Weed flora suggests an intensification of rice agriculture over time with increasing evidence of wetland weeds. We interpret these data as indicating early opportunistic cultivation of alluvial floodplains and some rainfed rice, developing into more systematic and probably irrigated cultivation starting in the Yangshao period, which intensified in the Qujialing and Shijiahe period, before a shift back to an emphasis on millets with the Late Longshan cultural influence from the north. PMID:26460975

  11. Predicting economic losses from the continued spread of the Mexican rice borer (Lepidoptera: Crambidae).

    PubMed

    Reay-Jones, F P F; Wilson, L T; Reagan, T E; Legendre, B L; Way, M O

    2008-04-01

    The Mexican rice borer, Eoreuma loftini (Dyar) (Lepidoptera: Crambidae), is an invasive species that originated from Mexico, and it is threatening to cause major economic losses to sugarcane, Saccharum spp., and rice, Oryza sativa L., industries in Louisiana. The insect is expected to reach sugarcane and rice production areas in Louisiana by 2008, and infest all of Louisiana sugarcane and rice industries by 2035. When all sugarcane in Louisiana becomes infested, annual yield losses of $220 million would be expected for a cultivar of comparable susceptibility to LCP 85-384 (assuming this cultivar is planted on 100% of the production area). This also assumes the use of the current practice of rainfed production and one application of insecticide, which is presently used by farmers in Louisiana. Irrigation with 30 cm of water is predicted to reduce estimated losses by 29%, whereas four applications of a biorational insecticide such as tebufenozide are expected to reduce the loss in revenue by 53%. The use of the resistant 'HoCP 85-845' would reduce the projected loss in revenue by 24%. Combining all three management tactics on sugarcane, anticipated net loss in revenue would decrease by 66%. The rice industry in Louisiana is projected to suffer from a loss in revenue of $45 million when the entire state is infested. A 77% reduction in loss in revenue is expected with one application of lambda-cyhalothrin. A quarantine on east Texas sugarcane is estimated to save the Louisiana industry between $1.1 billion and $3.2 billion (depending on management) during the time needed for the insect to fully invade the state's sugarcane and rice producing area by natural migration rather than by accidental introduction. The rapid deployment of appropriate management tactics will have a key role in reducing the anticipated economic impact of E. loftini once it becomes a pest in Louisiana sugarcane and rice.

  12. Synthetic Aperture Radar (SAR)-based paddy rice monitoring system: Development and application in key rice producing areas in Tropical Asia

    NASA Astrophysics Data System (ADS)

    Setiyono, T. D.; Holecz, F.; Khan, N. I.; Barbieri, M.; Quicho, E.; Collivignarelli, F.; Maunahan, A.; Gatti, L.; Romuga, G. C.

    2017-01-01

    Reliable and regular rice information is essential part of many countries’ national accounting process but the existing system may not be sufficient to meet the information demand in the context of food security and policy. Synthetic Aperture Radar (SAR) imagery is highly suitable for detecting lowland paddy rice, especially in tropical region where pervasive cloud cover in the rainy seasons limits the use of optical imagery. This study uses multi-temporal X-band and C-band SAR imagery, automated image processing, rule-based classification and field observations to classify rice in multiple locations across Tropical Asia and assimilate the information into ORYZA Crop Growth Simulation model (CGSM) to generate high resolution yield maps. The resulting cultivated rice area maps had classification accuracies above 85% and yield estimates were within 81-93% agreement against district level reported yields. The study sites capture much of the diversity in water management, crop establishment and rice maturity durations and the study demonstrates the feasibility of rice detection, yield monitoring, and damage assessment in case of climate disaster at national and supra-national scales using multi-temporal SAR imagery combined with CGSM and automated methods.

  13. Research in rice fields

    USGS Publications Warehouse

    ,

    2000-01-01

    Between 1987 and 1999, 2.4-3 million acres of rice were planted annually nationwide. Rice fields are a major component of the contemporary landscapes in the Gulf Coastal Plain, the Mississippi Alluvial Valley, and Central Valley of California. In 1998, approximately 600,000 acres of rice were planted in Louisiana. In the Louisiana plant commodities report for 1998, total value for rice was over $350 million; sugarcane was the only plant commodity that exceeded this value. Louisiana has over 2,000 rice farmers supporting over 12,000 jobs in the state. Rice fields in the United States receive high use by wildlife, especially shorebirds, wading birds, and waterfowl. Waterbirds use rice fields for food, shelter, and breeding habitat.

  14. The consequences of pleistocene climate change on lowland neotropical vegetation

    SciTech Connect

    De Oliveira, P.E.; Colinvaux, P.A. )

    1994-06-01

    Palynological reconstructions indicate that lowland tropical America was subject to intense cooling during the last ice-age. The descent of presently montane taxa into the lowlands of Amazonia and Minas Gerais indicate temperature depressions ranging from 5[degrees]C to 9[degrees]C cooler-than-present. The strengthened incursion of southerly airmasses caused a reassortment of vegetation throughout Amazonia. Presently allopatric species are found to have been sympatric as novel forest assemblages and formed and dissolved. Modest drying, perhaps a 20% reduction in precipitation, accounts for all the records that show a Pleistocene expansion of savanna. No evidence is found to support the fragmentation of Amazonian forests during glacial times, and the hypothesis of forest refuges as an explanation of tropical speciation is rejected on empirical grounds.

  15. The groundwater exchange rate of the southern Baltic coastal lowland

    NASA Astrophysics Data System (ADS)

    Burzyński, K.; Sadurski, A.

    1990-11-01

    The groundwater of the southern Baltic lowlands usually occurs in particular hydrogeological conditions. The lowland is mostly covered by peats several metres in thickness. Peatbog water is isolated from deeper aquifers and has different chemical composition. Salty, relic groundwater of marine origin from the Atlantic period of the Holocene (Littorina transgression) may have survived in the deeper coastal aquifers in places of sluggish flow. The results of mathematical modelling of groundwater circulation show that the flow rate and local directions of groundwater change during the year, depending on the rate of groundwater recharge by precipitation. We present here an unsteady flow model, which makes it possible to predict the water table fluctuations during a year at any point of the area studied. The calculation of the groundwater exchange rate did not confirm the presence of any places of very sluggish groundwater flow, where salty, young relic water might have survived.

  16. Postconflict behavior in captive western lowland gorillas (Gorilla gorilla gorilla).

    PubMed

    Mallavarapu, S; Stoinski, T S; Bloomsmith, M A; Maple, T L

    2006-08-01

    Postconflict (PC) behaviors, including reconciliation and consolation, have been observed in many primate and several nonprimate species. Using the PC-matched control (MC) method, PC behavior was examined in two groups (n=13) of captive western lowland gorillas, a species for which no conflict resolution data have been published. Analyses of 223 conflicts showed significantly more affiliation between former opponents after a conflict when compared to control periods, indicating reconciliation. Results also showed significantly more affiliation between the victim and a third-party after a conflict, indicating consolation. Both solicited and unsolicited consolation were observed. The majority of the affiliative interactions observed for both reconciliation and consolation were social proximity, which suggests that unlike most nonhuman primates, proximity, rather than physical contact, may be the main mechanism for resolving conflicts in western lowland gorillas. PC behavior was not uniform throughout the groups, but rather varied according to dyad type.

  17. Teleconnections of ENSO and IOD to summer monsoon and rice production potential of India

    NASA Astrophysics Data System (ADS)

    Jha, Somnath; Sehgal, Vinay Kumar; Raghava, Ramesh; Sinha, Mourani

    2016-12-01

    Regional trend of summer monsoon precipitation has been analyzed for broad physical regions of India namely, (i) Indo-Gangetic plain, (ii) Central and East India, (iii) Coastal and Peninsular India and (iv) Western India. A significantly drying trend has been found in the two regions namely, Indo-Gangetic plain and Central and East India with comparative seasonal rate of drying higher in the latter region. A complex relation between the regional trend of summer monsoon precipitation, global teleconnection parameters and rice production of the regions have been studied. El Niño-Southern Oscillation (ENSO) and Indian Ocean dipole (IOD) have a significant role in the precipitation anomaly of Indo-Gangetic plain unlike Central and East India where the ENSO only plays role as global teleconnection parameter. Rice production of Central and East India has been found to be affected adversely during the El Nino years. Central and East India is found to be the worst affected region compared to the Indo-Gangetic plain with respect to its fragile rainfed rice production potential and strong adverse teleconnection of El Nino on the rice production in this zone.

  18. Ammonia emissions from different fertilizing strategies in Mediterranean rainfed winter cereals

    NASA Astrophysics Data System (ADS)

    Bosch-Serra, Àngela D.; Yagüe, María R.; Teira-Esmatges, María R.

    2014-02-01

    Anthropogenic ammonia (NH3) emissions mainly result from agricultural activities where manure spreading plays a significant role. For a Mediterranean rainfed winter cereal system there is a lack of data regarding NH3 emissions. The aim of this work is to provide field data on N losses due to NH3 volatilization as a consequence of the introduction of slurries in fertilization strategies and also, to assess the influence of environmental conditions and slurry characteristics on emissions. The fertilizing strategies include the use of slurry from fattening pigs (PS), sows (PSS) and/or mineral fertilizer (M) as ammonium nitrate. Fertilizers were spread over the calcareous soil at sowing and/or at tillering at rates from 15 to 45 kg NH4+-N ha-1 for M and from 48.8 to 250.3 kg NH4+-N ha-1 for slurries. The NH3 emissions were quantified during three cropping seasons. Average losses from the total ammonium nitrogen applied ranged from 7 to 78% for M and from 6 to 64% for slurries and they were not directly proportional to the amounts of applied ammonium. The best results on NH3 volatilization reduction were registered when soil water content (SWC, 0-30 cm) was below 56% of its field capacity and also, when slurry dry matter (DM) was in the interval of 6.1-9.3% for PS or much lower (0.8%) for PSS. High slurry DM favoured crust formation and the lower rates promoted infiltration, both of which reduced NH3 emissions. Nevertheless, at tillering, the lower DM content was the most effective in controlling emissions (<9 kg NH3-N ha-1) and equalled M fertilizer in cumulative NH3 loss (p > 0.05). A single slurry application at tillering did not negatively affect yield biomass. The combining of recommended timing of applications with slurry DM content and SWC should allow producers to minimize volatilization while maintaining financial benefits.

  19. Modelling field scale water partitioning using on-site observations in sub-Saharan rainfed agriculture

    NASA Astrophysics Data System (ADS)

    Makurira, H.; Savenije, H. H. G.; Uhlenbrook, S.

    2009-08-01

    Smallholder rainfed farming systems generally realise sub-optimal crop yields which are largely attributed to dry spell occurrences during crop growth stages. However, with improved farming practices, it seems possible to significantly increase yield levels even with little and highly variable rainfall. The presented results follow research conducted in the Makanya catchment in northern Tanzania where gross rainfall amounts to less than 400 mm/season which is insufficient to support staple food crops (e.g. maize). Alternative cultivation techniques such as runoff harvesting and in-field micro-storage structures are compared. These techniques aim to reduce soil and nutrient loss from the field but, more importantly, promote in-field infiltration and water retention. Water balance components have been observed in order to study water partitioning processes under different cultivation techniques. Based on rainfall, soil evaporation, transpiration, runoff and soil moisture measurements, a water balance model has been developed to simulate soil moisture variations over the growing season. It appears that about 50% of the diverted water leaves the root zone through deep percolation. Modelling shows that during the field trials the average productive transpiration flow ranged between 1.1-1.4 mm d-1 in the trial plots compared to 0.7-1.0 mm d-1 under traditional tillage practice. Productive transpiration processes accounted for 23-29% while losses to deep percolation accounted for 33-48% of the available water. Conclusions from the research are that the innovations tested are effective in enhancing soil moisture retention at field scale and that diversions allow crop growth moisture conditions to be attained with early rains. It is also concluded that there is more scope for efficient utilisation of the diverted runoff water if storage structures could be installed to regulate water flow to the root zone when required.

  20. Assessment of agricultural drought in rainfed cereal production areas of northern China

    NASA Astrophysics Data System (ADS)

    Li, Rui; Tsunekawa, Atsushi; Tsubo, Mitsuru

    2017-02-01

    Agricultural drought assessment is an important tool for water management in water-scarce regions such as Inner Mongolia and northeastern China. Conventional methods have difficulty of clarifying long-term influences of drought on regional agricultural production. To accurately evaluate regional agricultural drought, we assessed the performance of drought indices by constructing a new assessment framework with three components: crop model calibration and validation, drought index calculation, and index assessment (standard period setting, mean value and agreement assessments). The Environmental Policy Integrated Climate (EPIC) model simulated well of county-level wheat and maize yields in the nine investigated counties. We calculated a major crop-specific index yield reduction caused by water stress (WSYR) in the EPIC crop model, by relating potential and rainfed yields. Using 26 agricultural drought cases, we compared WSYR with two meteorological drought indices: precipitation (P) and aridity index (AI). The results showed that WSYR had greater agreement (85 %) than either the precipitation (65 %) or aridity index (68 %). The temporal trend of the indices over the period 1962-2010 was tested using three approaches. The result via WSYR revealed a significant increase in the trend of agricultural drought in drought-prone counties, which could not be shown by the precipitation and aridity indices. Total number of dry year via WSYR from 1990s to 2000s increases more sharply than via P or AI. As shown by WSYR, the number of dry years in northeastern China and Inner Mongolia is generally increasing, particularly after the 2000s, in the western part of the study area. The study reveals the usefulness of the framework for drought index assessment and indicates the potential of WSYR and possible drought cases for drought classification.

  1. Assessment of agricultural drought in rainfed cereal production areas of northern China

    NASA Astrophysics Data System (ADS)

    Li, Rui; Tsunekawa, Atsushi; Tsubo, Mitsuru

    2015-10-01

    Agricultural drought assessment is an important tool for water management in water-scarce regions such as Inner Mongolia and northeastern China. Conventional methods have difficulty of clarifying long-term influences of drought on regional agricultural production. To accurately evaluate regional agricultural drought, we assessed the performance of drought indices by constructing a new assessment framework with three components: crop model calibration and validation, drought index calculation, and index assessment (standard period setting, mean value and agreement assessments). The Environmental Policy Integrated Climate (EPIC) model simulated well of county-level wheat and maize yields in the nine investigated counties. We calculated a major crop-specific index yield reduction caused by water stress (WSYR) in the EPIC crop model, by relating potential and rainfed yields. Using 26 agricultural drought cases, we compared WSYR with two meteorological drought indices: precipitation (P) and aridity index (AI). The results showed that WSYR had greater agreement (85 %) than either the precipitation (65 %) or aridity index (68 %). The temporal trend of the indices over the period 1962-2010 was tested using three approaches. The result via WSYR revealed a significant increase in the trend of agricultural drought in drought-prone counties, which could not be shown by the precipitation and aridity indices. Total number of dry year via WSYR from 1990s to 2000s increases more sharply than via P or AI. As shown by WSYR, the number of dry years in northeastern China and Inner Mongolia is generally increasing, particularly after the 2000s, in the western part of the study area. The study reveals the usefulness of the framework for drought index assessment and indicates the potential of WSYR and possible drought cases for drought classification.

  2. Conservation Agriculture Practices in Rainfed Uplands of India Improve Maize-Based System Productivity and Profitability

    PubMed Central

    Pradhan, Aliza; Idol, Travis; Roul, Pravat K.

    2016-01-01

    Traditional agriculture in rainfed uplands of India has been experiencing low agricultural productivity as the lands suffer from poor soil fertility, susceptibility to water erosion and other external pressures of development and climate change. A shift toward more sustainable cropping systems such as conservation agriculture production systems (CAPSs) may help in maintaining soil quality as well as improving crop production and farmer’s net economic benefit. This research assessed the effects over 3 years (2011–2014) of reduced tillage, intercropping, and cover cropping practices customized for maize-based production systems in upland areas of Odisha, India. The study focused on crop yield, system productivity and profitability through maize equivalent yield and dominance analysis. Results showed that maize grain yield did not differ significantly over time or among CAPS treatments while cowpea yield was considered as an additional yield in intercropping systems. Mustard and horsegram grown in plots after maize cowpea intercropping recorded higher grain yields of 25 and 37%, respectively, as compared to those without intercropping. Overall, the full CAPS implementation, i.e., minimum tillage, maize–cowpea intercropping and mustard residue retention had significantly higher system productivity and net benefits than traditional farmer practices, i.e., conventional tillage, sole maize cropping, and no mustard residue retention. The dominance analysis demonstrated increasing benefits of combining conservation practices that exceeded thresholds for farmer adoption. Given the use of familiar crops and technologies and the magnitude of yield and income improvements, these types of CAPS should be acceptable and attractive for smallholder farmers in the area. This in turn should support a move toward sustainable intensification of crop production to meet future household income and nutritional needs. PMID:27471508

  3. Climate variability impacts on rainfed cereal yields in west and northwest Iran.

    PubMed

    Nouri, Milad; Homaee, Mehdi; Bannayan, Mohammad

    2017-04-18

    In order to assess the response of wheat and barley to climate variability, the correlation between variations of yields with local and global climate variables was investigated in west and northwest Iran over 1982-2013. The global climate variables were the El Niño-Southern Oscillation (ENSO), Arctic Oscillation (AO), and North Atlantic Oscillation (NAO) signals. Further, minimum (T min), maximum (T max), and mean (T mean) temperature, diurnal temperature range (DTR), precipitation, and reference evapotranspiration (ET0) was used as local weather factors. Pearson's correlation coefficient was applied to analyze the relationships between climatic variables and yields. Unlike T min, T mean, ET0, and T max, the yields were significantly associated with the entire growing season (EGS) DTR in most sites. Therefore, considering weather extreme variables such as DTR sheds light on the crop-temperature interactions. It is also found that the April-May-June (AMJ), October-November-December (OND), and EGS rainfall variations markedly influence the yields. Unlike the AO and NAO indices, the Niño-4 and SOI (the ENSO-related signals) were significantly correlated with the OND and EGS precipitation and DTR. Thus, the ENSO anomalies highly impact rainfed yields through influencing the OND and EGS rainfall and DTR in the studied sites. As the correlation coefficient of the OND and July-August-September (JAS) Niño-4 with yields was significant (p < 0.05) for almost all locations, the JAS and OND Niño-4 may be a good proxy for cereal yield forecasting. Further, an insignificant increment and a significant reduction in yields are expected in La Niña and El Niño years, respectively, relative to neutral years.

  4. Climate variability impacts on rainfed cereal yields in west and northwest Iran

    NASA Astrophysics Data System (ADS)

    Nouri, Milad; Homaee, Mehdi; Bannayan, Mohammad

    2017-04-01

    In order to assess the response of wheat and barley to climate variability, the correlation between variations of yields with local and global climate variables was investigated in west and northwest Iran over 1982-2013. The global climate variables were the El Niño-Southern Oscillation (ENSO), Arctic Oscillation (AO), and North Atlantic Oscillation (NAO) signals. Further, minimum (T min), maximum (T max), and mean (T mean) temperature, diurnal temperature range (DTR), precipitation, and reference evapotranspiration (ET0) was used as local weather factors. Pearson's correlation coefficient was applied to analyze the relationships between climatic variables and yields. Unlike T min, T mean, ET0, and T max, the yields were significantly associated with the entire growing season (EGS) DTR in most sites. Therefore, considering weather extreme variables such as DTR sheds light on the crop-temperature interactions. It is also found that the April-May-June (AMJ), October-November-December (OND), and EGS rainfall variations markedly influence the yields. Unlike the AO and NAO indices, the Niño-4 and SOI (the ENSO-related signals) were significantly correlated with the OND and EGS precipitation and DTR. Thus, the ENSO anomalies highly impact rainfed yields through influencing the OND and EGS rainfall and DTR in the studied sites. As the correlation coefficient of the OND and July-August-September (JAS) Niño-4 with yields was significant (p < 0.05) for almost all locations, the JAS and OND Niño-4 may be a good proxy for cereal yield forecasting. Further, an insignificant increment and a significant reduction in yields are expected in La Niña and El Niño years, respectively, relative to neutral years.

  5. Climate variability impacts on rainfed cereal yields in west and northwest Iran

    NASA Astrophysics Data System (ADS)

    Nouri, Milad; Homaee, Mehdi; Bannayan, Mohammad

    2017-09-01

    In order to assess the response of wheat and barley to climate variability, the correlation between variations of yields with local and global climate variables was investigated in west and northwest Iran over 1982-2013. The global climate variables were the El Niño-Southern Oscillation (ENSO), Arctic Oscillation (AO), and North Atlantic Oscillation (NAO) signals. Further, minimum ( T min), maximum ( T max), and mean ( T mean) temperature, diurnal temperature range (DTR), precipitation, and reference evapotranspiration (ET0) was used as local weather factors. Pearson's correlation coefficient was applied to analyze the relationships between climatic variables and yields. Unlike T min, T mean, ET0, and T max, the yields were significantly associated with the entire growing season (EGS) DTR in most sites. Therefore, considering weather extreme variables such as DTR sheds light on the crop-temperature interactions. It is also found that the April-May-June (AMJ), October-November-December (OND), and EGS rainfall variations markedly influence the yields. Unlike the AO and NAO indices, the Niño-4 and SOI (the ENSO-related signals) were significantly correlated with the OND and EGS precipitation and DTR. Thus, the ENSO anomalies highly impact rainfed yields through influencing the OND and EGS rainfall and DTR in the studied sites. As the correlation coefficient of the OND and July-August-September (JAS) Niño-4 with yields was significant ( p < 0.05) for almost all locations, the JAS and OND Niño-4 may be a good proxy for cereal yield forecasting. Further, an insignificant increment and a significant reduction in yields are expected in La Niña and El Niño years, respectively, relative to neutral years.

  6. Conservation Agriculture Practices in Rainfed Uplands of India Improve Maize-Based System Productivity and Profitability.

    PubMed

    Pradhan, Aliza; Idol, Travis; Roul, Pravat K

    2016-01-01

    Traditional agriculture in rainfed uplands of India has been experiencing low agricultural productivity as the lands suffer from poor soil fertility, susceptibility to water erosion and other external pressures of development and climate change. A shift toward more sustainable cropping systems such as conservation agriculture production systems (CAPSs) may help in maintaining soil quality as well as improving crop production and farmer's net economic benefit. This research assessed the effects over 3 years (2011-2014) of reduced tillage, intercropping, and cover cropping practices customized for maize-based production systems in upland areas of Odisha, India. The study focused on crop yield, system productivity and profitability through maize equivalent yield and dominance analysis. Results showed that maize grain yield did not differ significantly over time or among CAPS treatments while cowpea yield was considered as an additional yield in intercropping systems. Mustard and horsegram grown in plots after maize cowpea intercropping recorded higher grain yields of 25 and 37%, respectively, as compared to those without intercropping. Overall, the full CAPS implementation, i.e., minimum tillage, maize-cowpea intercropping and mustard residue retention had significantly higher system productivity and net benefits than traditional farmer practices, i.e., conventional tillage, sole maize cropping, and no mustard residue retention. The dominance analysis demonstrated increasing benefits of combining conservation practices that exceeded thresholds for farmer adoption. Given the use of familiar crops and technologies and the magnitude of yield and income improvements, these types of CAPS should be acceptable and attractive for smallholder farmers in the area. This in turn should support a move toward sustainable intensification of crop production to meet future household income and nutritional needs.

  7. Inland valley rice production systems and malaria infection and disease in the savannah of Côte d'Ivoire.

    PubMed

    Henry, M-C; Rogier, C; Nzeyimana, I; Assi, S B; Dossou-Yovo, J; Audibert, M; Mathonnat, J; Keundjian, A; Akodo, E; Teuscher, T; Carnevale, P

    2003-05-01

    In sub-Saharan Africa, lowlands developed for rice cultivation favour the development of Anopheles gambiae s. l. populations. However, the epidemiological impact is not clearly determined. The importance of malaria was compared in terms of prevalence and parasite density of infections as well as in terms of disease incidence between three agroecosystems: (i) uncultivated lowlands, 'R0', (ii) lowlands with one annual rice cultivation in the rainy season, 'R1' and (iii) developed lowlands with two annual rice cultivation cycles, 'R2'. We clinically monitored 2000 people of all age groups, selected randomly in each agroecosystem, for 40 days (in eight periods of five consecutive days scheduled every 6 weeks for 1 year). During each survey, a systematic blood sample was taken from every sick and asymptomatic person. The three agroecosystems presented a high endemic situation with a malaria transmission rate of 139-158 infective bites per person per year. The age-standardized annual malaria incidence reached 0.9 malaria episodes per person in R0, 0.6 in R1 and 0.8 in R2. Children from 0 to 9-year-old in R0 and R2 had two malarial attacks annually, but this was less in R1 (1.4 malaria episodes per child per year). Malaria incidence varied with season and agroecosystem. In parallel with transmission, a high malaria risk occurs temporarily at the beginning of the dry season in R2, but not in R0 and R1. Development of areas for rice cultivation does not modify the annual incidence of malarial attacks despite their seasonal influence on malaria risk. However, the lower malaria morbidity rate in R1 could be explained by socio-economic and cultural factors.

  8. A water storage adaptation in the maya lowlands.

    PubMed

    Scarborough, V L; Gallopin, G G

    1991-02-08

    Prehispanic water management in the Maya Lowlands emphasized collection and storage rather than the canalization and diversion accentuated in highland Mexico. Reexamination of site maps of the ancient Maya city of Tikal, Guatemala, has revealed an important, overlooked factor in Maya centralization and urban settlement organization. In a geographical zone affected by an extended dry season and away from permanent water sources, large, well-planned reservoirs provided resource control as well as political leverage.

  9. Distribution of coastal morphology in the Martian northern lowlands

    NASA Technical Reports Server (NTRS)

    Parker, T. J.; Gorsline, D. S.

    1992-01-01

    The northern plains of Mars exhibit boundary morphologies that were interpreted as shorelines of a sea that formed as a result of flooding from the major outflow channel along the periphery of the lowlands. Earlier work focused on a morphologic description based on the very high resolution images available in the west Deuteronilus Mensae region where these boundaries and their relationships to pre-existing features could be most readily characterized. Here, we wish to describe the criteria used in the earlier identification.

  10. Biological and physical conditions of macroinvertebrates in reference lowland streams

    NASA Astrophysics Data System (ADS)

    de Brouwer, Jan; Eekhout, Joris; Verdonschot, Piet

    2016-04-01

    Channelisation measures taken halfway the 20th century have had destructive consequences for the diversity of the ecology in the majority of the lowland streams in countries such as the Netherlands. Currently, stream restoration measures are being implemented in these degraded lowland streams, where design principles are often based on outdated relationships between biological and physical conditions. Little is known about the reference conditions in these streams. Therefore, the aim of this research is to quantify the relationships between biological and physical conditions of macroinvertebrates in reference lowland streams. The research was conducted in four near-natural lowland streams in Central Poland. Field data were obtained during a field campaign in 2011. The following data were obtained in a 50-m reach in each of the four streams: macroinvertebrate sampling, spatial habitat patterns, bathymetry, and flow-velocity. Furthermore, water level, light sensitivity and temperature sensors were installed to obtain the temporal dynamic of these streams. Macroinvertebrates were sampled in 9 different habitat types, i.e. sand, gravel, fine organic matter, stones, branches, leaves, silt, vegetation, and wood. Macroinvertebrates were determined to the highest taxonomic level possible. Data from the bathymetrical surveys were interpolated on a grid and bathymetrical metrics were determined. Flow velocity measurements were related to habitats and flow velocity metrics were determined. Analysis of the data shows that flow conditions vary among the different habitat, with a gradient from hard substrates towards soft substrates. Furthermore, the data show that stream as a unit best explains species composition, but also specific habitat conditions, such as substrate type and flow velocity, correlate with species composition. More specific, the data shows a strong effect of wood on species composition. These findings may have implications for stream restoration design, which

  11. Flow controls on lowland river macrophytes: a review.

    PubMed

    Franklin, Paul; Dunbar, Michael; Whitehead, Paul

    2008-08-01

    We review the current status of knowledge regarding the role that flow parameters play in controlling the macrophyte communities of temperate lowland rivers. We consider both direct and indirect effects and the interaction with other factors known to control macrophyte communities. Knowledge gaps are identified and implications for the management of river systems considered. The main factors and processes controlling the status of macrophytes in lowland rivers are velocity (hence also discharge), light, substrate, competition, nutrient status and river management practices. We suggest that whilst the characteristics of any particular macrophyte community reflect the integral effects of a combination of the factors, fundamental importance can be attributed to the role of discharge and velocity in controlling instream macrophyte colonisation, establishment and persistence. Velocity and discharge also appear to control the relative influence of some of the other controlling factors. Despite the apparent importance of velocity in determining the status of macrophyte communities in lowland rivers, relatively little is understood about the nature of the processes controlling this relationship. Quantitative knowledge is particularly lacking. Consequently, the ability to predict macrophyte abundance and distribution in rivers is still limited. This is further complicated by the likely existence of feedback effects between the growth of macrophytes and velocity. Demand for water resources increases the pressure on lowland aquatic ecosystems. Despite growing recognition of the need to allocate water for the needs of instream biota, the inability to assess the flow requirements of macrophyte communities limits the scope to achieve this. This increases the likelihood of overexploitation of the water resource as other users, whose demands are quantifiable, are prioritised.

  12. Morphological Assessment of Reconstructed Lowland Streams in the Netherlands

    NASA Astrophysics Data System (ADS)

    Hoitink, T.; Eekhout, J.; de Brouwer, J.; Verdonschot, P.

    2014-12-01

    Channelisation measures taken halfway the 20th century have had destructive consequences for the diversity of the ecology in the majority of the lowland streams in countries such as the Netherlands. Re-meandering is the common practice in restoring these lowland streams. Three lowland streams were monitored during the initial two years after construction of a new channel. The monitoring program included morphological surveys, sediment sampling, habitat pattern surveys, and discharge and water level measurements. Adjustments of the longitudinal bed profile formed the main morphological response. These adjustments were most likely caused by a lack of longitudinal connectivity of the streams as a whole, interrupting transport of sediment at locations of weirs and culverts. Bank erosion was observed only in a limited number of channel bends, and was often related to floodplain heterogeneity. Longitudinal channel bed adjustments and bank erosion were mainly caused by exogenous influences. In channel bends, the cross-sectional shape transformed from trapezoidal to the typical asymmetrical shape as found in meandering rivers. This behaviour can be attributed to an autogenous response to the prevailing flow conditions. Due to the prevailing fine sediment characteristics, bed material is readily set in motion and is being transported during the entire year. The existing design principles fail to address the initial morphological development after reconstruction. An evaluation of pre-set targets to realize water depth and flow velocity ranges shows the current procedures to be deficient. Based on this unfavourable evaluation, and the two-dimensional nature of habitat patterns needed to improve the conditions for stream organisms, we recommend to predict morphological developments as part of the design procedures for lowland stream restoration in the Netherlands.

  13. Prediction of kharif rice yield at Kharagpur using disaggregated extended range rainfall forecasts

    NASA Astrophysics Data System (ADS)

    Dhekale, B. S.; Nageswararao, M. M.; Nair, Archana; Mohanty, U. C.; Swain, D. K.; Singh, K. K.; Arunbabu, T.

    2017-08-01

    The Extended Range Forecasts System (ERFS) has been generating monthly and seasonal forecasts on real-time basis throughout the year over India since 2009. India is one of the major rice producer and consumer in South Asia; more than 50% of the Indian population depends on rice as staple food. Rice is mainly grown in kharif season, which contributed 84% of the total annual rice production of the country. Rice cultivation in India is rainfed, which depends largely on rains, so reliability of the rainfall forecast plays a crucial role for planning the kharif rice crop. In the present study, an attempt has been made to test the reliability of seasonal and sub-seasonal ERFS summer monsoon rainfall forecasts for kharif rice yield predictions at Kharagpur, West Bengal by using CERES-Rice (DSSATv4.5) model. These ERFS forecasts are produced as monthly and seasonal mean values and are converted into daily sequences with stochastic weather generators for use with crop growth models. The daily sequences are generated from ERFS seasonal (June-September) and sub-seasonal (July-September, August-September, and September) summer monsoon (June to September) rainfall forecasts which are considered as input in CERES-rice crop simulation model for the crop yield prediction for hindcast (1985-2008) and real-time mode (2009-2015). The yield simulated using India Meteorological Department (IMD) observed daily rainfall data is considered as baseline yield for evaluating the performance of predicted yields using the ERFS forecasts. The findings revealed that the stochastic disaggregation can be used to disaggregate the monthly/seasonal ERFS forecasts into daily sequences. The year to year variability in rice yield at Kharagpur is efficiently predicted by using the ERFS forecast products in hindcast as well as real time, and significant enhancement in the prediction skill is noticed with advancement in the season due to incorporation of observed weather data which reduces uncertainty of

  14. Lowland tapir distribution and habitat loss in South America.

    PubMed

    Cordeiro, Jose Luis Passos; Fragoso, José M V; Crawshaw, Danielle; Oliveira, Luiz Flamarion B

    2016-01-01

    The development of species distribution models (SDMs) can help conservation efforts by generating potential distributions and identifying areas of high environmental suitability for protection. Our study presents a distribution and habitat map for lowland tapir in South America. We also describe the potential habitat suitability of various geographical regions and habitat loss, inside and outside of protected areas network. Two different SDM approaches, MAXENT and ENFA, produced relative different Habitat Suitability Maps for the lowland tapir. While MAXENT was efficient at identifying areas as suitable or unsuitable, it was less efficient (when compared to the results by ENFA) at identifying the gradient of habitat suitability. MAXENT is a more multifaceted technique that establishes more complex relationships between dependent and independent variables. Our results demonstrate that for at least one species, the lowland tapir, the use of a simple consensual approach (average of ENFA and MAXENT models outputs) better reflected its current distribution patterns. The Brazilian ecoregions have the highest habitat loss for the tapir. Cerrado and Atlantic Forest account for nearly half (48.19%) of the total area lost. The Amazon region contains the largest area under protection, and the most extensive remaining habitat for the tapir, but also showed high levels of habitat loss outside protected areas, which increases the importance of support for proper management.

  15. Lowland tapir distribution and habitat loss in South America

    PubMed Central

    Fragoso, José M.V.; Crawshaw, Danielle; Oliveira, Luiz Flamarion B.

    2016-01-01

    The development of species distribution models (SDMs) can help conservation efforts by generating potential distributions and identifying areas of high environmental suitability for protection. Our study presents a distribution and habitat map for lowland tapir in South America. We also describe the potential habitat suitability of various geographical regions and habitat loss, inside and outside of protected areas network. Two different SDM approaches, MAXENT and ENFA, produced relative different Habitat Suitability Maps for the lowland tapir. While MAXENT was efficient at identifying areas as suitable or unsuitable, it was less efficient (when compared to the results by ENFA) at identifying the gradient of habitat suitability. MAXENT is a more multifaceted technique that establishes more complex relationships between dependent and independent variables. Our results demonstrate that for at least one species, the lowland tapir, the use of a simple consensual approach (average of ENFA and MAXENT models outputs) better reflected its current distribution patterns. The Brazilian ecoregions have the highest habitat loss for the tapir. Cerrado and Atlantic Forest account for nearly half (48.19%) of the total area lost. The Amazon region contains the largest area under protection, and the most extensive remaining habitat for the tapir, but also showed high levels of habitat loss outside protected areas, which increases the importance of support for proper management. PMID:27672509

  16. How Ebola Impacts Genetics of Western Lowland Gorilla Populations

    PubMed Central

    Le Gouar, Pascaline J.; Vallet, Dominique; David, Laetitia; Bermejo, Magdalena; Gatti, Sylvain; Levréro, Florence; Petit, Eric J.; Ménard, Nelly

    2009-01-01

    Background Emerging infectious diseases in wildlife are major threats for both human health and biodiversity conservation. Infectious diseases can have serious consequences for the genetic diversity of populations, which could enhance the species' extinction probability. The Ebola epizootic in western and central Africa induced more than 90% mortality in Western lowland gorilla population. Although mortality rates are very high, the impacts of Ebola on genetic diversity of Western lowland gorilla have never been assessed. Methodology/Principal Findings We carried out long term studies of three populations of Western lowland gorilla in the Republic of the Congo (Odzala-Kokoua National Park, Lossi gorilla sanctuary both affected by Ebola and Lossi's periphery not affected). Using 17 microsatellite loci, we compared genetic diversity and structure of the populations and estimate their effective size before and after Ebola outbreaks. Despite the effective size decline in both populations, we did not detect loss in genetic diversity after the epizootic. We revealed temporal changes in allele frequencies in the smallest population. Conclusions/Significance Immigration and short time elapsed since outbreaks could explain the conservation of genetic diversity after the demographic crash. Temporal changes in allele frequencies could not be explained by genetic drift or random sampling. Immigration from genetically differentiated populations and a non random mortality induced by Ebola, i.e., selective pressure and cost of sociality, are alternative hypotheses. Understanding the influence of Ebola on gorilla genetic dynamics is of paramount importance for human health, primate evolution and conservation biology. PMID:20020045

  17. Anatomy of simultaneous flood peaks at a lowland confluence

    NASA Astrophysics Data System (ADS)

    Geertsema, Tjitske; Teuling, Ryan; Uijlenhoet, Remko; Torfs, Paul; Weerts, Albrecht; Hoitink, Ton

    2017-04-01

    Lowlands are vulnerable to flooding due to their mild topography in often densely populated areas with high social and economic value. Moreover, multiple physical processes coincide in lowland areas, such as those involved in river-sea interactions and in merging of rivers. Simultaneous occurrence of such processes can result in amplifying or attenuating effects on water levels. The aim of this study is to understand the mechanisms behind simultaneous occurrence of flood peak events in the main river and tributaries in delta areas, taking the confluence of the Meuse river with the Dommel/Aa tributary as an example. Especially since the January 1995 flood at this confluence is analyzed as result of the simultaneous occurrence of discharge peaks. This study shows that simultaneous occurrence of flood peak events is common in the lowland area of the Meuse with the tributaries Dommel and Aa, because discharge peaks last long; on average 9 days in the Meuse. A typical lag time of about 3 days between tributaries and main river does not prevent simultaneous occurrence. The simultaneous occurrence of the discharge peaks results in a water level gradient increase in the main river and decrease in the tributaries, which show backwater effects of up to 1.5 meters.

  18. Effects of Traditional Flood Irrigation on Invertebrates in Lowland Meadows

    PubMed Central

    Schirmel, Jens; Alt, Martin; Rudolph, Isabell; Entling, Martin H.

    2014-01-01

    Lowland meadow irrigation used to be widespread in Central Europe, but has largely been abandoned during the 20th century. As a result of agri-environment schemes and nature conservation efforts, meadow irrigation is now being re-established in some European regions. In the absence of natural flood events, irrigation is expected to favour fauna typical of lowland wet meadows. We analysed the effects of traditional flood irrigation on diversity, densities and species composition of three invertebrate indicator taxa in lowland meadows in Germany. Unexpectedly, alpha diversity (species richness and Simpson diversity) and beta diversity (multivariate homogeneity of group dispersions) of orthopterans, carabids, and spiders were not significantly different between irrigated and non-irrigated meadows. However, spider densities were significantly higher in irrigated meadows. Furthermore, irrigation and elevated humidity affected species composition and shifted assemblages towards moisture-dependent species. The number of species of conservation concern, however, did not differ between irrigated and non-irrigated meadows. More variable and intensive (higher duration and/or frequency) flooding regimes might provide stronger conservation benefits, additional species and enhance habitat heterogeneity on a landscape scale. PMID:25340872

  19. Cooked rice texture and rice flour pasting properties; impacted by rice temperature during milling.

    PubMed

    Saleh, Mohammed; Meullenet, Jean-Francois

    2015-03-01

    Rice milling plays a key factor in determining rice quality and value. Therefore accurate quality assessments are critical to the rice industry. This study was undertaken to assess the effect of exposing rice to elevated temperatures during milling, on cooked rice texture and rice flour pasting properties. Two long (Cybonnett and Francis) and one medium (Jupiter) rice (oryzae sativa L.) cultivars were milled using McGill laboratory mill for 30 and 40 s after warmed up the mill before milling. Four different milling temperatures per milling duration were achieved. Cooked rice texture properties were assessed using a uniaxial compression test and rice flour pasting properties measured using a TA-2000 rheometer. Results of this study showed that exposure of rice to high temperatures during milling significantly decreased cooked rice firmness. An increase in milled rice temperature after milling from 10.0 to 13.3 °C resulted in a 5.4 and 8.1 N decrease in cooked rice firmness. Although not always significant, the increase in milled rice temperature during milling resulted in an increase in cooked rice stickiness. The increase in milling temperature also showed significant increase in rice flour pasting properties. Changes in rice functional characteristics were attributed to the changes occurring to rice chemical constituents due to temperature exposure as indicated by the increase in rice protein hydrophobicity. Proteins are known to affect rice starch water holding capacity and other starch gelatinization properties.

  20. Towards Global Simulation of Irrigation in a Land Surface Model: Multiple Cropping and Rice Paddy in Southeast Asia

    NASA Technical Reports Server (NTRS)

    Beaudoing, Hiroko Kato; Rodell, Matthew; Ozdogan, Mutlu

    2010-01-01

    Agricultural land use significantly influences the surface water and energy balances. Effects of irrigation on land surface states and fluxes include repartitioning of latent and sensible heat fluxes, an increase in net radiation, and an increase in soil moisture and runoff. We are working on representing irrigation practices in continental- to global-scale land surface simulation in NASA's Global Land Data Assimilation System (GLDAS). Because agricultural practices across the nations are diverse, and complex, we are attempting to capture the first-order reality of the regional practices before achieving a global implementation. This study focuses on two issues in Southeast Asia: multiple cropping and rice paddy irrigation systems. We first characterize agricultural practices in the region (i.e., crop types, growing seasons, and irrigation) using the Global data set of monthly irrigated and rainfed crop areas around the year 2000 (MIRCA2000) dataset. Rice paddy extent is identified using remote sensing products. Whether irrigated or rainfed, flooded fields need to be represented and treated explicitly. By incorporating these properties and processes into a physically based land surface model, we are able to quantify the impacts on the simulated states and fluxes.

  1. Towards Global Simulation of Irrigation in a Land Surface Model: Multiple Cropping and Rice Paddy in Southeast Asia

    NASA Technical Reports Server (NTRS)

    Beaudoing, Hiroko Kato; Rodell, Matthew; Ozdogan, Mutlu

    2010-01-01

    Agricultural land use significantly influences the surface water and energy balances. Effects of irrigation on land surface states and fluxes include repartitioning of latent and sensible heat fluxes, an increase in net radiation, and an increase in soil moisture and runoff. We are working on representing irrigation practices in continental- to global-scale land surface simulation in NASA's Global Land Data Assimilation System (GLDAS). Because agricultural practices across the nations are diverse, and complex, we are attempting to capture the first-order reality of the regional practices before achieving a global implementation. This study focuses on two issues in Southeast Asia: multiple cropping and rice paddy irrigation systems. We first characterize agricultural practices in the region (i.e., crop types, growing seasons, and irrigation) using the Global data set of monthly irrigated and rainfed crop areas around the year 2000 (MIRCA2000) dataset. Rice paddy extent is identified using remote sensing products. Whether irrigated or rainfed, flooded fields need to be represented and treated explicitly. By incorporating these properties and processes into a physically based land surface model, we are able to quantify the impacts on the simulated states and fluxes.

  2. Elucidation of rice rhizosphere metagenome in relation to methane and nitrogen metabolism under elevated carbon dioxide and temperature using whole genome metagenomic approach.

    PubMed

    Bhattacharyya, P; Roy, K S; Das, M; Ray, S; Balachandar, D; Karthikeyan, S; Nayak, A K; Mohapatra, T

    2016-01-15

    Carbon (C) and nitrogen (N) mineralization is one of the key processes of biogeochemical cycling in terrestrial ecosystem in general and rice ecology in particular. Rice rhizosphere is a rich niche of microbial diversity influenced by change in atmospheric temperature and concentration of carbon dioxide (CO2). Structural changes in microbial communities in rhizosphere influence the nutrient cycling. In the present study, the bacterial diversity and population dynamics were studied under ambient CO2 (a-CO2) and elevated CO2+temperature (e-CO2T) in lowland rice rhizosphere using whole genome metagenomic approach. The whole genome metagenomic sequence data of lowland rice exhibited the dominance of bacterial communities including Proteobacteria, Firmicutes, Acidobacteria, Actinobacteria and Planctomycetes. Interestingly, four genera related to methane production namely, Methanobacterium, Methanosphaera, Methanothermus and Methanothermococcus were absent in a-CO2 but noticed under e-CO2T. The acetoclastic pathway was found as the predominant pathway for methanogenesis, whereas, the serine pathway was found as the principal metabolic pathway for CH4 oxidation in lowland rice. The abundances of reads of enzymes in the acetoclastic methanogenesis pathway and serine pathways of methanotrophy were much higher in e-CO2T (328 and 182, respectively) as compared with a-CO2 (118 and 98, respectively). Rice rhizosphere showed higher structural diversities and functional activities in relation to N metabolism involving nitrogen fixation, assimilatory and dissimilatory nitrate reduction and denitrification under e-CO2T than that of a-CO2. Among the three pathways of N metabolism, dissimilarity pathways were predominant in lowland rice rhizosphere and more so under e-CO2T. Consequently, under e-CO2T, CH4 emission, microbial biomass nitrogen (MBN) and dehydrogenase activities were 45%, 20% and 35% higher than a-CO2, respectively. Holistically, a high bacterial diversity and

  3. Biochar helps enhance maize productivity and reduce greenhouse gas emissions under balanced fertilization in a rainfed low fertility inceptisol.

    PubMed

    Zhang, Dengxiao; Pan, Genxing; Wu, Gang; Kibue, Grace Wanjiru; Li, Lianqing; Zhang, Xuhui; Zheng, Jinwei; Zheng, Jufeng; Cheng, Kun; Joseph, Stephen; Liu, Xiaoyu

    2016-01-01

    Maize production plays an important role in global food security, especially in arid and poor-soil regions. Its production is also increasing in China in terms of both planting area and yield. However, maize productivity in rainfed croplands is constrained by low soil fertility and moisture insufficiency. To increase the maize yield, local farmers use NPK fertilizer. However, the fertilization regime (CF) they practice is unbalanced with too much nitrogen in proportion to both phosphorus and potassium, which has led to low fertilizer use efficiency and excessive greenhouse gases emissions. A two-year field experiment was conducted to assess whether a high yielding but low greenhouse gases emission system could be developed by the combination of balanced fertilization (BF) and biochar amendment in a rainfed farmland located in the Northern region of China. Biochar was applied at rates of 0, 20, and 40 t/ha. Results show that BF and biochar increased maize yield and partial nutrient productivity and decreased nitrous oxide (N2O) emission. Under BF the maize yield was 23.7% greater than under CF. N2O emissions under BF were less than half that under CF due to a reduced N fertilizer application rate. Biochar amendment decreased N2O by more than 31% under CF, while it had no effect on N2O emissions under BF. Thus BF was effective at maintaining a high maize yield and reducing greenhouse gases emissions. If combined with biochar amendment, BF would be a good way of sustaining low carbon agriculture in rainfed areas.

  4. Multiscale object-based drought monitoring and comparison in rainfed and irrigated agriculture from Landsat 8 OLI imagery

    NASA Astrophysics Data System (ADS)

    Ozelkan, Emre; Chen, Gang; Ustundag, Burak Berk

    2016-02-01

    Drought is a rapidly rising environmental issue that can cause hardly repaired or unrepaired damages to the nature and socio-economy. This is especially true for a region that features arid/semi-arid climate, including the Turkey's most important agricultural district - Southeast Anatolia. In this area, we examined the uncertainties of applying Landsat 8 Operational Land Imager (OLI) NDVI data to estimate meteorological drought - Standardized Precipitation Index (SPI) - measured from 31 in-situ agro-meteorological monitoring stations during spring and summer of 2013 and 2014. Our analysis was designed to address two important, yet under-examined questions: (i) how does the co-existence of rainfed and irrigated agriculture affect remote sensing drought monitoring in an arid/semi-arid region? (ii) What is the role of spatial scale in drought monitoring using a GEOBIA (geographic object-based image analysis) framework? Results show that spatial scale exerted a higher impact on drought monitoring especially in the drier year 2013, during which small scales were found to outperform large scales in general. In addition, consideration of irrigated and rainfed areas separately ensured a better performance in drought analysis. Compared to the positive correlations between SPI and NDVI over the rainfed areas, negative correlations were determined over the irrigated agricultural areas. Finally, the time lag effect was evident in the study, i.e., strong correlations between spring SPI and summer NDVI in both 2013 and 2014. This reflects the fact that spring watering is crucial for the growth and yield of the major crops (i.e., winter wheat, barley and lentil) cultivated in the region.

  5. Carbon Pool of Permafrost in Kolyma-Indigirka Lowland

    NASA Astrophysics Data System (ADS)

    Shmelev, D.; Veremeeva, A.; Kraev, G.; Kholodov, A. L.; Rivkina, E.

    2014-12-01

    The original database of total carbon, bulk density and iciness and new Geological map were compiled for carbon pool permafrost estimating in Quaternary deposits of North East Yakutia. The database was based on original drilling data on the main Quaternary stratigraphic units of Kolyma-Indigirka Lowland (12 key sites, 120 boreholes, 1000 samples). New geological map was created according Landsat-7 Satellite Image (spatial resolution - 30 m), the State Geological map of Quaternary Deposits (2000) and our field investigation for last 30 years in studying region. Studying area was divided into 3 regions according stratigraphy: East of Yana-Indigirka Lowland, Chukochya and Alazeya Rivers basins, East of Kolyma Lowland. Estimating was compiled for upper 25 m thickness.4 main geomorphological levels were selected for calculation: yedoma (12,8% of total area), alasses (48%), river valley (20,9%) and coastal accumulative lowland (16,7%). Our studies shows, that distribution of yedoma was overestimated in 3,5 times by State Geological Map, mainly due to underestimating of allases (increasing area on 60%).According our assessment, inorganic carbon doesn't exceed 10% of total carbon in the studying area. Permafrost stratigraphic units contain 0.6-2.1% of TC, with the highest concentrations found in Cover Layer and Ice Complex (Yedoma). The biggest carbon pool is found in Olyor, which refers to the most widespread sediments studied and high carbon concentration (up to 18 kg*m-3). The TC pool of Yedoma was 1.5-2 times overestimated by previous studies due to less samples and underestimated iciness. The TC pool of Kolyma delta is 5-7 times overestimated because of higher total organic carbon values considered. Taking the morphology into account, the TC pool assessed is 23.4 ± 9.5 Gt at near 95 000 km2 area. Mean specific carbon content is around 9.9 kg*m-3 in Kolyma Lowland permafrost. The stratigraphic unit-based approach used to compile the database and its analysis provides

  6. Characterizing groundwater contribution to lowland streams using Travel Time Distribution

    NASA Astrophysics Data System (ADS)

    Petrus Kaandorp, Vincentius; Gerardus Bernardus de Louw, Petrus; Kuijper, Martina Johanna Maria; Broers, Hans Peter

    2015-04-01

    In recent years, it has become apparent that European freshwaters will fail to meet the ecological guidelines set for 2015 by the Water Framework Directive. 55 % of European surface water bodies have been reported to have a less than good ecological status, while the goal for 2015 is to have a good status for all water bodies. The deterioration of freshwater aquatic ecosystems is a problem worldwide. The current study, part of the EU FP7 project Managing Aquatic ecosystems and water Resources under multiple Stress (MARS), addresses this issue by focusing on the effect of multiple stressors. Freshwater ecosystems are directly linked to the characteristics of catchments and streams they are located in as this determines the habitats present. One of these characteristics, the groundwater contribution to streams, is important for aquatic ecosystems as it influences (1) river discharge, (2) water quality and (3) temperature and (4) the riparian zone. Groundwater provides streams with sufficient base flow, good quality water and a stable temperature. Compared to hilly slope catchments, the lowland catchments of The Netherlands lack much topography and surface runoff, and as such, virtually all stream water originates from groundwater. Current approaches do not sufficiently address the contribution of groundwater to stream flow in lowland catchments, as existing hydrograph separation methods provide little informative value about the groundwater contribution itself. The amount and quality of groundwater input to streams depends on its flow path and travel time. Especially in lowland catchments the groundwater input in streams is composed of a wide range of travel times which vary in time and space and have different quantitative and qualitative characteristics. Thus in order to successfully manage lowland streams, it is critical to specify the input of groundwater in more detail and take in account the temporal and spatial variability in travel times. We will present an

  7. Breeding high-yielding drought-tolerant rice: genetic variations and conventional and molecular approaches

    PubMed Central

    Kumar, Arvind; Dixit, Shalabh; Ram, T.; Yadaw, R. B.; Mishra, K. K.; Mandal, N. P.

    2014-01-01

    The increased occurrence and severity of drought stress have led to a high yield decline in rice in recent years in drought-affected areas. Drought research at the International Rice Research Institute (IRRI) over the past decade has concentrated on direct selection for grain yield under drought. This approach has led to the successful development and release of 17 high-yielding drought-tolerant rice varieties in South Asia, Southeast Asia, and Africa. In addition to this, 14 quantitative trait loci (QTLs) showing a large effect against high-yielding drought-susceptible popular varieties were identified using grain yield as a selection criterion. Six of these (qDTY 1.1, qDTY 2.2, qDTY 3.1, qDTY 3.2, qDTY 6.1, and qDTY 12.1) showed an effect against two or more high-yielding genetic backgrounds in both the lowland and upland ecosystem, indicating their usefulness in increasing the grain yield of rice under drought. The yield of popular rice varieties IR64 and Vandana has been successfully improved through a well-planned marker-assisted backcross breeding approach, and QTL introgression in several other popular varieties is in progress. The identification of large-effect QTLs for grain yield under drought and the higher yield increase under drought obtained through the use of these QTLs (which has not been reported in other cereals) indicate that rice, because of its continuous cultivation in two diverse ecosystems (upland, drought tolerant, and lowland, drought susceptible), has benefited from the existence of larger genetic variability than in other cereals. This can be successfully exploited using marker-assisted breeding. PMID:25205576

  8. Characterising Groundwater-dominated Lowland Catchments - the UK Lowland Catchment Research Programme (LOCAR)

    NASA Astrophysics Data System (ADS)

    Wheater, H. S.; Peach, D.; Binley, A.

    2005-12-01

    This paper reports on a major 10million UK initiative to address deficiencies in understanding the hydro-ecological response of groundwater-dominated lowland catchments. We focus here on one of three sets of research basins - the Pang/Lambourn Chalk catchments, tributaries of the river Thames in southern England. The motivation for the research is the need to support integrated management of river systems that have high ecological value and are subject to pressures that include groundwater abstraction for water supply, diffuse pollution, and land use and climate change. We give an overview of the experimental approach and highlight some current research findings. Despite the importance of the Chalk as a major UK aquifer, knowledge of the subsurface movement of water and solutes is poor. Solute transport in the dual porosity unsaturated zone depends on fracture/matrix interactions that are difficult to observe; current experimental and modelling research supports the predominance of matrix flow and suggests that slow migration of a time-history of decades of nutrient loading is occurring. Groundwater flows are complex; catchments vary seasonally and are ill-defined and Karst features are locally important. Groundwater flow pathways are being investigated using natural and artificial geochemical tracers based on experimental borehole arrays; stream-aquifer interaction research is using a combination of geophysics, borehole array geochemistry and longitudinal profiles of stream flow and solutes. A complex picture is emerging of localised subsurface inflows, linked to structural geological controls and karst features, and significant longitudinal groundwater flow below the river channel. Hyporheic zone research has shown significant areas of methanogenesis and denitrification - the catchment-scale significance of this remains to be determined. Similarly, analysis of nutrient transformations in riparian wetlands is being linked to analysis of groundwater flowpaths to

  9. Characterising groundwater-dominated lowland catchments: the UK Lowland Catchment Research Programme (LOCAR)

    NASA Astrophysics Data System (ADS)

    Wheater, H. S.; Peach, D.; Binley, A.

    2007-01-01

    This paper reports on a major UK initiative to address deficiencies in understanding the hydro-ecological response of groundwater-dominated lowland catchments. The scope and objectives of this national programme are introduced and focus on one of three sets of research basins - the Pang/Lambourn Chalk catchments, tributaries of the river Thames in southern England. The motivation for the research is the need to support integrated management of river systems that have high ecological value and are subject to pressures that include groundwater abstraction for water supply, diffuse pollution, and land use and climate change. An overview of the research programme is provided together with highlights of some current research findings concerning the hydrological functioning of these catchments. Despite the importance of the Chalk as a major UK aquifer, knowledge of the subsurface movement of water and solutes is poor. Solute transport in the dual porosity unsaturated zone depends on fracture/matrix interactions that are difficult to observe; current experimental and modelling research supports the predominance of matrix flow and suggests that slow migration of a time-history of decades of nutrient loading is occurring. Groundwater flows are complex; catchments vary seasonally and are ill-defined and karst features are locally important. Groundwater flow pathways are being investigated using natural and artificial geochemical tracers based on experimental borehole arrays; stream-aquifer interaction research is using a combination of geophysics, borehole array geochemistry and longitudinal profiles of stream flow and solutes. A complex picture of localised subsurface inflows, linked to geological controls and karst features, and significant longitudinal groundwater flow below the river channel is emerging. Management implications are discussed. Strategies to control surface application of nutrients are expected to have little effect on groundwater quality for several

  10. Mitigation options for methane emissions from rice fields in the Philippines

    SciTech Connect

    Lantin, R.S.; Buendia, L.V.; Wassmann, R.

    1996-12-31

    The contribution of Philippine rice production to global methane emission and breakthroughs in methane emission studies conducted in the country are presented in this paper. A significant impact in the reduction of GHG emissions from agriculture can be achieved if methane emissions from ricefields can be abated. This study presents the contribution of Philippine rice cultivation to global methane emission and breakthroughs in methane emission studies in the country which address the issue of mitigation. Using the derived emission factors from local measurements, rice cultivation contributes 566.6 Gg of methane emission in the Philippines. This value is 62% of the total methane emitted from the agriculture sector. The emission factors employed which are 78% of the IPCC value for irrigated rice and 95% for rainfed rice were derived from measurements with an automatic system taken during the growth duration in the respective ecosystems. Plots drained for 2 weeks at midtillering and before harvest gave a significant reduction in methane emission as opposed to continuously flooded plots and plots drained before harvest. The cultivar Magat reduced methane emission by 50% as compared to the check variety IR72. The application of ammonium sulfate instead of urea reduced methane emission by 10% to 34%. Addition of 6 t ha{sup {minus}1} phosphogypsum in combination with urea reduced emission by 74% as opposed to plots applied with urea alone. It is also from the results of such measurements that abatement strategies are based as regards to modifying treatments such as water management, fertilization, and choice of rice variety. It is not easy to identify and recommend mitigation strategies that will fit a particular cropping system. However, the identified mitigation options provide focus for the abatement of methane emission from ricefields.

  11. How Will Climate Change Impact Water Consumption for Rice Irrigation in Southern Brazil?

    NASA Astrophysics Data System (ADS)

    dos Santos, T. V.; Twine, T. E.

    2015-12-01

    Globally, agricultural water use accounts for most of the water that is withdrawn from surface water and groundwater. Rice, one of the world's leading food crops, requires that fields be continuously flooded to obtain optimal yields. High air temperature and consecutive rainless days in rice-growing areas can significantly reduce rice yields, leading to food scarcity. Climate change is expected to affect water demand for rice via changes in rainfall regime, soil water balance, and evapotranspiration. Higher temperatures and increased variability of precipitation are predicted to increase water demand and could potentially require more irrigation in lowland rice-growing areas. In this study we present the first results from model simulations in which we integrated a rice model into the Agro-IBIS dynamic ecosystem model. We predict the impact of climate change on the water use requirement of rice production in southern Brazil and evaluate changes in irrigation needed to meet minimum water demand to sustain current yields. Brazil is the 9th top rice producer in the world, and southern Brazil accounts for about 80% of the national production. The Agro-IBIS model was driven with historic weather data provided by CRU (1961-90) and with two future climate scenarios from the Coupled Model Intercomparison Project Phase 5 (CMIP5) for 2015-2100 - Representative Concentration Pathways 4.5 (RCP45) and 8.5 (RCP85). On an hourly time step, Agro-IBIS accounts for gains (precipitation) and losses (evaporation, transpiration, infiltration and runoff) of water in each grid cell, and uses rules to irrigate in order to maintain a specific height of standing water on the field. Simulated historic and future amounts of irrigated water needed to maintain this water height will be evaluated to predict future water demand for rice production in southern Brazil.

  12. Modelling field scale water partitioning using on-site observations in sub-Saharan rainfed agriculture

    NASA Astrophysics Data System (ADS)

    Makurira, H.; Savenije, H. H. G.; Uhlenbrook, S.

    2010-04-01

    Smallholder rainfed farming systems generally realise sub-optimal crop yields which are largely attributed to dry spell occurrences during crop growth stages. However, through the introduction of appropriate farming practices, it is possible to substantially increase yield levels even with little and highly variable rainfall. The presented results follow research conducted in the Makanya catchment in northern Tanzania where gross rainfall amounts to less than 400 mm/season which is insufficient to support staple food crops (e.g. maize). The yields from farming system innovations (SIs), which are basically alternative cultivation techniques, are compared against traditional farming practices. The SIs tested in this research are runoff harvesting used in combination with in-field trenches and soil bunds (fanya juus). These SIs aim to reduce soil and nutrient loss from the field and, more importantly, promote in-field infiltration and water retention. Water balance components have been observed in order to study water partitioning processes for the "with" and "without" SI scenarios. Based on rainfall, soil evaporation, transpiration, runoff and soil moisture measurements, a water balance model has been developed to simulate soil moisture variations over the growing season. Simulation results show that, during the field trials, the average productive transpiration flow ranged between 1.1-1.4 mm d-1 in the trial plots compared to 0.7-1.0 mm d-1 under traditional tillage practice. Productive transpiration processes accounted for 23-29% while losses to deep percolation accounted for 33-48% of the available water. The field system has been successfully modelled using the spreadsheet-based water balance 1-D model. Conclusions from the research are that the SIs that were tested are effective in enhancing soil moisture retention at field scale and that diversions allow crop growth moisture conditions to be attained with early rains. From the partitioning analysis, it is also

  13. Regional Climate Change Scenarios for Mexico and Potential Impacts on Rainfed Maize Agriculture.

    NASA Astrophysics Data System (ADS)

    Conde, C.; Estrada, F.; Martínez, B.; Sánchez, O.; Monterroso, A.; Rosales, G.; Gay, C.

    2010-03-01

    Regional climate change scenarios that were used to assess the potential impacts on different sectors in Mexico are presented, with an application of those scenarios for the agricultural sector. The results of that research were delivered to the Mexican government for the development of the Mexican Fourth National Communication, which will be presented to the United Nations Framework Convention on Climate Change (UNFCCC). To generate regional climate change scenarios the models and criteria suggested by the Intergovernmental Panel on Climate Change (IPCC) in its Fourth Assessment Report (4AR) were applied. Those criteria are: Consistency with global projections, Physical plausibility, Applicability in impact assessments, Representative of the potential range of changes in the future, Accessibility for the users of impacts assessments. The regional scenarios that were generated focus mainly on the applicability and accessibility criteria. A kick-off meeting was held at the beginning of the research work for the Fourth National Communication, to ensure that those criteria were fulfilled. Specifically, a set of climate change scenarios was generated using the outputs for temperature and precipitation of three General Circulation Models (GCMs): ECHAM5, HADGEM1 y GFDL CM2.0, for the horizons 2030 and 2050, and for the emission scenarios A1B, A2, B2 y B1. Those scenarios can be found in our web page in a low spatial resolution (2.5 º x 2.5º), and with high resolution (5’ x 5’). To assess the potential impacts on rainfed maize agriculture, the changes of the suitability of different regions in the country were evaluated, considering maize temperature and precipitation requirements at its different stages of development. Four categories of suitability (high, moderated, marginal, and no suitable) were characterized for current and future climatic conditions. Using the A2 and B2 emission scenarios, the three GCMs and the horizon 2050, results showed that around 67% of

  14. From rainfed agriculture to stress-avoidance irrigation: I. A generalized irrigation scheme with stochastic soil moisture

    NASA Astrophysics Data System (ADS)

    Vico, Giulia; Porporato, Amilcare

    2011-02-01

    With vast regions already experiencing water shortages, it is becoming imperative to manage sustainably the available water resources. As agriculture is by far the most important user of freshwater and the role of irrigation is projected to increase in face of climate change and increased food requirements, it is particularly important to develop simple, widely applicable models of irrigation water needs for short- and long-term water resource management. Such models should synthetically provide the key irrigation quantities (volumes, frequencies, etc.) for different irrigation schemes as a function of the main soil, crop, and climatic features, including rainfall unpredictability. Here we consider often-employed irrigation methods (e.g., surface and sprinkler irrigation systems, as well as modern micro-irrigation techniques) and describe them under a unified conceptual and theoretical framework, which includes rainfed agriculture and stress-avoidance irrigation as extreme cases. We obtain mostly analytical solutions for the stochastic steady state of soil moisture probability density function with random rainfall timing and amount, and compute water requirements as a function of climate, crop, and soil parameters. These results provide the necessary starting point for a full assessment of irrigation strategies, with reference to sustainability, productivity, and profitability, developed in a companion paper [Vico G, Porporato A. From rainfed agriculture to stress-avoidance irrigation: II. Sustainability, crop yield, and net profit. Adv Water Resour 2011;34(2):272-81].

  15. Development of a decision support system for small reservoir irrigation systems in rainfed and drought prone areas.

    PubMed

    Balderama, Orlando F

    2010-01-01

    An integrated computer program called Cropping System and Water Management Model (CSWM) with a three-step feature (expert system-simulation-optimization) was developed to address a range of decision support for rainfed farming, i.e. crop selection, scheduling and optimisation. The system was used for agricultural planning with emphasis on sustainable agriculture in the rainfed areas through the use of small farm reservoirs for increased production and resource conservation and management. The application of the model was carried out using crop, soil, and climate and water resource data from the Philippines. Primarily, four sets of data representing the different rainfall classification of the country were collected, analysed, and used as input in the model. Simulations were also done on date of planting, probabilities of wet and dry period and with various capacities of the water reservoir used for supplemental irrigation. Through the analysis, useful information was obtained to determine suitable crops in the region, cropping schedule and pattern appropriate to the specific climate conditions. In addition, optimisation of the use of the land and water resources can be achieved in areas partly irrigated by small reservoirs.

  16. Determinants for grading Malaysian rice

    NASA Astrophysics Data System (ADS)

    ChePa, Noraziah; Yusoff, Nooraini; Ahmad, Norhayati

    2016-08-01

    Due to un-uniformity of rice grading practices in Malaysia, zones which actively producing rice in Malaysia are using their own way of grading rice. Rice grading is important in determining rice quality and its subsequent price in the market. It is an important process applied in the rice production industry with the purpose of ensuring that the rice produced for the market meets the quality requirements of consumer. Two important aspects that need to be considered in determining rice grades are grading technique and determinants to be used for grading (usually referred as rice attributes). This article proposes the list of determinants to be used in grading Malaysian rice. Determinants were explored through combination of extensive literature review and series of interview with the domain experts and practitioners. The proposed determinants are believed to be beneficial to BERNAS in improving the current Malaysian rice grading process.

  17. Relating raw rice color and composition to cooked rice color.

    USDA-ARS?s Scientific Manuscript database

    Traditionally, the color of milled rice is economically important. The whiter the rice the more it is preferred by consumers and the more value it has in the market place. Little attention has been given to relating raw rice color to cooked milled rice color and, specifically, to determining the i...

  18. Exchange of nitrous oxide within the Hudson Bay lowland

    NASA Technical Reports Server (NTRS)

    Schiller, C. L.; Hastie, D. R.

    1994-01-01

    The source strength of atmospheric trace gases from natural ecosystems must be quantified in order to assess the effect of such inputs on the background tropospheric chemistry. A static chamber technique and a gas exchange technique were used to determine the emissions of nitrous oxide from five sites within the Hudson Bay Lowland, as part of the Northern Wetland Study. Two mechanisms, one diffusive and the other episodic, were found likely to be responsible for the emissions of nitrous oxide. The annual diffusive flux ranged from -3.8 mg(N2O)/sq m in a treed bog to 7.9 mg(N2O)/sq m in an open fen. The addition of the episodic flux, increased this range to -2.1 mg(N2O)/sq m and 18.5 mg(N2O)/sq m respectively. These episodic emissions occurred in from 2.5% to 16.7% of the samples during the late summer peak emission period. Since the gas exchange rate could not detect the episodic emissions, it was found to be a poor method for water emission rate determination within the wetland. LANDSAT-Thermatic Mapper (TM) imagery was used to scale the emissions, from the chamber level to an integrated average over the entire Hudson Bay Lowland. The total emission rate of N2O from the Hudson Bay Lowland, was determined to be 1.2 Gg(N2O)/year, of which 80% was attributed to episodic emissions.

  19. Herbicide contamination and dispersion pattern in lowland springs.

    PubMed

    Laini, Alex; Bartoli, Marco; Lamastra, Lucrezia; Capri, Ettore; Balderacchi, Matteo; Trevisan, Marco

    2012-11-01

    Herbicides reduce the diversity of flora and fauna in freshwater ecosystems and also contaminate groundwater due to leaching. Herbicide contamination can be a serious threat for all groundwater-dependent ecosystems (GDE), altering their chemical and biological quality. Successful management to protect GDE is dependent on detailed knowledge of the hydrogeological and hydrochemical features of the surrounding environment. We consider the possible diffuse contamination by herbicides of groundwater and of GDE as lowland springs, semi-artificial ecosystems with elevated biodiversity. The main objectives of the present work were thus: (1) to map herbicide contamination in lowland springs, (2) to evaluate the potential risk for biota and (3) to quantify the extent of the area from which the herbicide use can affect the water quality of lowland springs. In June and August 2009, nearly 23 springs within the Po River Plain (Northern Italy) were sampled and analyzed for five herbicides used to control weeds in maize. Hydrogeological properties, half-lives of the herbicides and their concentrations in both groundwater and springs were used to quantify the area from which the contamination could originate. Such evaluation was performed by means of GIS techniques. Terbuthylazine were the only herbicide found, together with its metabolite desethylterbuthylazine. In 16 out of 84 measurements, their concentrations were above the threshold for drinking water; however, they were always below the ecotoxicological end-points of aquatic flora and fauna. Spatial analyses reveal that the theoretical area from which herbicides can contaminate spring water is within a distance varying between a few and 1800 m. Our findings indicate that conservation plans should focus on the fields adjacent to or surrounding the springs and should address the optimization of irrigation practices, restoration of buffer strips, crop rotation and in general more sustainable agricultural practices in the

  20. Morphological assessment of reconstructed lowland streams in the Netherlands

    NASA Astrophysics Data System (ADS)

    Eekhout, Joris P. C.; Hoitink, Antonius J. F.; de Brouwer, Jan H. F.; Verdonschot, Piet F. M.

    2015-07-01

    Channelisation measures taken halfway the 20th century have had destructive consequences for the diversity of the ecology in the majority of the lowland streams in countries such as the Netherlands. Re-meandering is the common practice in restoring these lowland streams. Three reconstructed streams were monitored during the initial two years after construction of a new channel. The monitoring program included morphological surveys, sediment sampling, habitat pattern surveys, and discharge and water level measurements. Adjustments of the longitudinal bed profile formed the main morphological response. These adjustments were most likely caused by a lack of longitudinal connectivity of the streams as a whole, interrupting transport of sediment at locations of weirs and culverts. Bank erosion was observed only in a limited number of channel bends, and was often related to floodplain heterogeneity. Longitudinal channel bed adjustments and bank erosion were mainly caused by exogenous influences. In channel bends, the cross-sectional shape transformed from trapezoidal to the typical asymmetrical shape as found in meandering rivers. This behaviour can be attributed to an autogenous response to the prevailing flow conditions. Due to the prevailing fine sediment characteristics, bed material is readily set in motion and is being transported during the entire year. The existing design principles fail to address the initial morphological development after reconstruction. An evaluation of pre-set targets to realise water depth and flow velocity ranges shows the current procedures to be deficient. Based on this unfavourable evaluation, and the two-dimensional nature of habitat patterns needed to improve the conditions for stream organisms, we recommend to predict morphological developments as part of the design procedures for lowland stream restoration in the Netherlands.

  1. Hydrology of inland tropical lowlands: the Kapuas and Mahakam wetlands

    NASA Astrophysics Data System (ADS)

    Hidayat, Hidayat; Teuling, Adriaan J.; Vermeulen, Bart; Taufik, Muh; Kastner, Karl; Geertsema, Tjitske J.; Bol, Dinja C. C.; Hoekman, Dirk H.; Sri Haryani, Gadis; Van Lanen, Henny A. J.; Delinom, Robert M.; Dijksma, Roel; Anshari, Gusti Z.; Ningsih, Nining S.; Uijlenhoet, Remko; Hoitink, Antonius J. F.

    2017-05-01

    Wetlands are important reservoirs of water, carbon and biodiversity. They are typical landscapes of lowland regions that have high potential for water retention. However, the hydrology of these wetlands in tropical regions is often studied in isolation from the processes taking place at the catchment scale. Our main objective is to study the hydrological dynamics of one of the largest tropical rainforest regions on an island using a combination of satellite remote sensing and novel observations from dedicated field campaigns. This contribution offers a comprehensive analysis of the hydrological dynamics of two neighbouring poorly gauged tropical basins; the Kapuas basin (98 700 km2) in West Kalimantan and the Mahakam basin (77 100 km2) in East Kalimantan, Indonesia. Both basins are characterised by vast areas of inland lowlands. Hereby, we put specific emphasis on key hydrological variables and indicators such as discharge and flood extent. The hydroclimatological data described herein were obtained during fieldwork campaigns carried out in the Kapuas over the period 2013-2015 and in the Mahakam over the period 2008-2010. Additionally, we used the Tropical Rainfall Measuring Mission (TRMM) rainfall estimates over the period 1998-2015 to analyse the distribution of rainfall and the influence of El-Niño - Southern Oscillation. Flood occurrence maps were obtained from the analysis of the Phase Array type L-band Synthetic Aperture Radar (PALSAR) images from 2007 to 2010. Drought events were derived from time series of simulated groundwater recharge using time series of TRMM rainfall estimates, potential evapotranspiration estimates and the threshold level approach. The Kapuas and the Mahakam lake regions are vast reservoirs of water of about 1000 and 1500 km2 that can store as much as 3 and 6.5 billion m3 of water, respectively. These storage capacity values can be doubled considering the area of flooding under vegetation cover. Discharge time series show that

  2. Rice (Oryza) hemoglobins

    USDA-ARS?s Scientific Manuscript database

    Hemoglobins (Hbs) corresponding to non-symbiotic (nsHb) and truncated (tHb) Hbs have been identified in rice (Oryza). This review discusses the major findings from the current studies on rice Hbs. At the molecular level, a family of the nshb genes, consisting of hb1, hb2, hb3, hb4 and hb5, and a sin...

  3. Making rice even healthier!

    USDA-ARS?s Scientific Manuscript database

    Rice is a naturally healthy food, but what if it could be made even healthier? Would Americans eat more rice if it could be advertised to be a 'New and Improved' source of calcium to promote bone growth, or iron to prevent anemia? Grocery stores are full of foods that are vitamin enhanced to attract...

  4. Multiple abiotic stimuli are integrated in the regulation of rice gene expression under field conditions.

    PubMed

    Plessis, Anne; Hafemeister, Christoph; Wilkins, Olivia; Gonzaga, Zennia Jean; Meyer, Rachel Sarah; Pires, Inês; Müller, Christian; Septiningsih, Endang M; Bonneau, Richard; Purugganan, Michael

    2015-11-26

    Plants rely on transcriptional dynamics to respond to multiple climatic fluctuations and contexts in nature. We analyzed the genome-wide gene expression patterns of rice (Oryza sativa) growing in rainfed and irrigated fields during two distinct tropical seasons and determined simple linear models that relate transcriptomic variation to climatic fluctuations. These models combine multiple environmental parameters to account for patterns of expression in the field of co-expressed gene clusters. We examined the similarities of our environmental models between tropical and temperate field conditions, using previously published data. We found that field type and macroclimate had broad impacts on transcriptional responses to environmental fluctuations, especially for genes involved in photosynthesis and development. Nevertheless, variation in solar radiation and temperature at the timescale of hours had reproducible effects across environmental contexts. These results provide a basis for broad-based predictive modeling of plant gene expression in the field.

  5. The influence of nitrogen fertiliser rate and crop rotation on soil methane flux in rain-fed potato fields in Wuchuan County, China.

    PubMed

    Wang, Liwei; Pan, Zhihua; Xu, Hui; Wang, Cheng; Gao, Lin; Zhao, Peiyi; Dong, Zhiqiang; Zhang, Jingting; Cui, Guohui; Wang, Sen; Han, Guolin; Zhao, Hui

    2015-12-15

    As one of the important greenhouse gases, the characteristics and principles of methane exchange characteristics in cultivated lands have become hot topics in current climate change research. This study examines the influences of nitrogen fertilisation, temperature and soil water content on methane exchange characteristic and methane exchange functional gene-pmoA gene abundance based on experimental observations of methane exchange fluxes using the static chamber-gas chromatographic method and measurements of methanotroph gene copy numbers in three growing periods by real-time PCR in rain-fed potato fields. The results indicate that the rain-fed potato fields were a CH4 sink with an average annual methane absorption (negative emission) of 940.8±103.2 g CH4-C/ha/year. The cumulative methane absorption first exhibited flat and subsequently increasing trend with the increase of nitrogen fertilisation from 0~135 kg N·ha(-1). Methane cumulative absorption significantly increased with the increase of temperature when temperatures were below 19.6 °C. Methane oxidation capacity (methanotroph pmoA gene copy numbers) showed an increasing and subsequently decreasing trend with the increase of soil moisture. Crop rotation was observed to increase the methane absorption in rain-fed potato fields and nearly one time higher than that under continuous cropping. A mechanism concept model of the methane exchange in rain-fed potato fields was advanced in this paper.

  6. Fine mapping of RBG2, a quantitative trait locus for resistance to Burkholderia glumae, on rice chromosome 1.

    PubMed

    Mizobuchi, Ritsuko; Sato, Hiroyuki; Fukuoka, Shuichi; Tsushima, Seiya; Yano, Masahiro

    Bacterial grain rot (BGR), caused by the bacterial pathogen Burkholderia glumae, is a destructive disease of rice. At anthesis, rice panicles are attacked by the pathogen, and the infection causes unfilled or aborted grains, reducing grain yield and quality. Thus, increasing the level of BGR resistance is an important objective for rice breeding. A quantitative trait locus (QTL) on rice chromosome 1 that controls BGR resistance was previously detected in backcross inbred lines (BILs) derived from a cross between Kele, a resistant traditional lowland cultivar (indica) that originated in India, and Hitomebore, a susceptible modern lowland cultivar (temperate japonica) from Japan. Further genetic analyses using a BC3F6 population derived from a cross between a resistant BIL (BC2F5) and Hitomebore confirmed that a QTL for BGR resistance was located on the long arm of chromosome 1. To define more precisely the chromosomal region underlying this QTL, we identified nine BC2F6 plants in which recombination occurred near the QTL. Substitution mapping using homozygous recombinant and nonrecombinant plants demonstrated that the QTL, here designated as Resistance to Burkholderia glumae 2 (RBG2), was located in a 502-kb interval defined by simple sequence repeat markers RM1216 and RM11727.

  7. Groundwater head controls nitrate export from an agricultural lowland catchment

    NASA Astrophysics Data System (ADS)

    Musolff, Andreas; Schmidt, Christian; Rode, Michael; Lischeid, Gunnar; Weise, Stephan M.; Fleckenstein, Jan H.

    2016-10-01

    Solute concentration variability is of fundamental importance for the chemical and ecological state of streams. It is often closely related to discharge variability and can be characterized in terms of a solute export regime. Previous studies, especially in lowland catchments, report that nitrate is often exported with an accretion pattern of increasing concentrations with increasing discharge. Several modeling approaches exist to predict the export regime of solutes from the spatial relationship of discharge generating zones with solute availability in the catchment. For a small agriculturally managed lowland catchment in central Germany, we show that this relationship is controlled by the depth to groundwater table and its temporal dynamics. Principal component analysis of groundwater level time series from wells distributed throughout the catchment allowed derivation of a representative groundwater level time series that explained most of the discharge variability. Groundwater sampling revealed consistently decreasing nitrate concentrations with an increasing thickness of the unsaturated zone. The relationships of depth to groundwater table to discharge and to nitrate concentration were parameterized and integrated to successfully model catchment discharge and nitrate export on the basis of groundwater level variations alone. This study shows that intensive and uniform agricultural land use likely results in a clear and consistent concentration-depth relationship of nitrate, which can be utilized in simple approaches to predict stream nitrate export dynamics at the catchment scale.

  8. The puzzling origin of the Martian Northern Lowlands.

    NASA Astrophysics Data System (ADS)

    Altieri, F.; Carrozzo, G.; Carli, C.; Geminale, A.; Bellucci, G.

    Surface studies of the northern lowlands of Mars have shown that this region has undergone a complex history including volcanism, sedimentary deposition and secondary modification by climate change. Despite these analyses, the origin and the evolution of this region are still debated. No clear and definitive evidences have been found so far to conclude whether these plains were formed by a giant impact, were once covered by an ocean or were filled by a large quantity of lavas. In the visible and infrared spectral range, the northern lowlands differ from southern terrains in the NIR negative slope while they exhibit VNIR spectra similar to the southern pyroxene-rich areas (Carrozzo et al., 2012). These observations, combined with both recent detection of mafic minerals at higher spatial resolution by CRISM (Salvatore et al., 2010) and recent results of Horgan and Bell (2012), supports that their mineralogy is linked to weathered basalts with a glassy component. In addition to this, the spectral similarity of Acidalia area with the northern circumpolar sand dunes, apart from the hydration features, suggests that the weathering processes that took place there could be related to past glacial activity, in agreement with superficial morphology showing glacial structures. Aim of this work is to combine the OMEGA mineralogical maps with morphological features (Tanaka et al., 2011) and investigate possible terrestrial analogues in order to give some constrains on the composition and origin of these puzzling Martian terrains.

  9. Spatial and temporal heterogeneity of water soil erosion in a Mediterranean rain-fed crop

    NASA Astrophysics Data System (ADS)

    López-Vicente, M.; Quijano, L.; Gaspar, L.; Machín, J.; Navas, A.

    2012-04-01

    Fertile soil loss by raindrop impact and runoff processes in croplands presents significant variations at temporal and spatial scales. The combined use of advanced GIS techniques and detailed databases allows high resolution mapping of runoff and soil erosion processes. In this study the monthly values of soil loss are calculated in a medium size field of rain-fed winter barley and its drainage area located in the Central Spanish Pre-Pyrenees. The field is surrounded by narrow strips of dense Mediterranean vegetation (mainly holm oaks) and grass. Man-made infrastructures (paved trails and drainage ditches) modify the overland flow pathways and the study site appears hydrologically closed in its northern and western boundaries. This area has a continental Mediterranean climate with two humid periods, one in spring and a second in autumn and a dry summer with rainfall events of high intensity from July to October. The average annual rainfall is 495 mm and the average monthly rainfall intensity ranges from 1.1 mm / h in January to 7.4 mm / h in July. The predicted rates were obtained after running the RMMF model (Morgan, 2001) with the enhancements made to this model by Morgan and Duzant (2008) to the topographic module, and by López-Vicente and Navas (2010) to the hydrological module. A total of 613 soil samples were collected and all input and output maps were generated at high spatial resolution (1 x 1 m of cell size) with ArcMapTM 10.0. A map of effective cumulative runoff was calculated for each month of the year with a weighted multiple flow algorithm and four sub-catchments were distinguished within the field. The average soil erosion in the cultivated area is 1.32 Mg / ha yr and the corresponding map shows a high spatial variability (s.d. = 7.52 Mg / ha yr). The highest values of soil erosion appear in those areas where overland flow is concentrated and slope steepness is higher. The unpaved trail present the highest values of soil erosion with an average

  10. About climate variabilitiy leading the hydric condition of the soil in the rainfed region of Argentina

    NASA Astrophysics Data System (ADS)

    Pántano, V. C.; Penalba, O. C.

    2013-05-01

    Extreme events of temperature and rainfall have a socio-economic impact in the rainfed agriculture production region in Argentina. The magnitude of the impact can be analyzed through the water balance which integrates the characteristics of the soil and climate conditions. Changes observed in climate variables during the last decades affected the components of the water balance. As a result, a displacement of the agriculture border towards the west was produced, improving the agricultural production of the region. The objective of this work is to analyze how the variability of rainfall and temperature leads the hydric condition of the soil, with special focus on extreme events. The hydric conditions of the soil (HC= Excess- Deficit) were estimated from the monthly water balance (Thornthwaite and Mather method, 1957), using monthly potential evapotranspiration (PET) and monthly accumulated rainfall (R) for 33 stations (period 1970-2006). Information of temperature and rainfall was provided by National Weather Service and the effective capacity of soil water was considered from Forte Lay and Spescha (2001). An agricultural extreme condition occurs when soil moisture and rainfall are inadequate or excessive for the development of the crops. In this study, we define an extreme event when the variable is less (greater) than its 20% and 10% (80% and 90%) percentile. In order to evaluate how sensitive is the HC to water and heat stress in the region, different conditional probabilities were evaluated. There is a weaker response of HC to extreme low PET while extreme low R leads high values of HC. However, this behavior is not always observed, especially in the western region where extreme high and low PET show a stronger influence over the HC. Finally, to analyze the temporal variability of extreme PET and R, leading hydric condition of the soil, the number of stations presenting extreme conditions was computed for each month. As an example, interesting results were

  11. Preliminary Studies of the Performance of Quinoa (Chenopodium quinoa Willd.) Genotypes under Irrigated and Rainfed Conditions of Central Malawi.

    PubMed

    Maliro, Moses F A; Guwela, Veronica F; Nyaika, Jacinta; Murphy, Kevin M

    2017-01-01

    The goal of sustainable intensification of agriculture in Malawi has led to the evaluation of innovative, regionally novel or under-utilized crop species. Quinoa (Chenopodium quinoa Willd.) has the potential to provide a drought tolerant, nutritious alternative to maize. We evaluated 11 diverse varieties of quinoa for their yield and agronomic performance at two locations, Bunda and Bembeke, in Malawi. The varieties originated from Ecuador, Chile and Bolivia in South America; the United States and Canada in North America; and, Denmark in Europe, and were chosen based on their variation in morphological and agronomic traits, and their potential for adaptation to the climate of Malawi. Plant height, panicle length, days to maturity, harvest index, and seed yield were recorded for each variety under irrigation at Bunda and Bembeke, and under rainfed conditions at Bunda. Plant height was significantly influenced by both genotype and environment. There were also significant differences between the two locations for panicle length whereas genotype and genotype × environment (G × E) interaction were not significantly different. Differences were found for genotype and G × E interaction for harvest index. Notably, differences for genotype, environment and G × E were found for grain yield. Seed yield was higher at Bunda (237-3019 kg/ha) than Bembeke (62-692 kg/ha) under irrigated conditions. The highest yielding genotype at Bunda was Titicaca (3019 kg/ha) whereas Multi-Hued was the highest (692 kg/ha) at Bembeke. Strong positive correlations between seed yield and (1) plant height (r = 0.74), (2) days to maturity (r = 0.76), and (3) biomass (r = 0.87) were found under irrigated conditions. The rainfed evaluations at Bunda revealed significant differences in seed yield, plant biomass, and seed size among the genotypes. The highest yielding genotype was Black Seeded (2050 kg/ha) followed by Multi-Hued (1603 kg/ha) and Bio-Bio (1446 kg/ha). Ecuadorian (257 kg/ha) was the

  12. Preliminary Studies of the Performance of Quinoa (Chenopodium quinoa Willd.) Genotypes under Irrigated and Rainfed Conditions of Central Malawi

    PubMed Central

    Maliro, Moses F. A.; Guwela, Veronica F.; Nyaika, Jacinta; Murphy, Kevin M.

    2017-01-01

    The goal of sustainable intensification of agriculture in Malawi has led to the evaluation of innovative, regionally novel or under-utilized crop species. Quinoa (Chenopodium quinoa Willd.) has the potential to provide a drought tolerant, nutritious alternative to maize. We evaluated 11 diverse varieties of quinoa for their yield and agronomic performance at two locations, Bunda and Bembeke, in Malawi. The varieties originated from Ecuador, Chile and Bolivia in South America; the United States and Canada in North America; and, Denmark in Europe, and were chosen based on their variation in morphological and agronomic traits, and their potential for adaptation to the climate of Malawi. Plant height, panicle length, days to maturity, harvest index, and seed yield were recorded for each variety under irrigation at Bunda and Bembeke, and under rainfed conditions at Bunda. Plant height was significantly influenced by both genotype and environment. There were also significant differences between the two locations for panicle length whereas genotype and genotype × environment (G × E) interaction were not significantly different. Differences were found for genotype and G × E interaction for harvest index. Notably, differences for genotype, environment and G × E were found for grain yield. Seed yield was higher at Bunda (237–3019 kg/ha) than Bembeke (62–692 kg/ha) under irrigated conditions. The highest yielding genotype at Bunda was Titicaca (3019 kg/ha) whereas Multi-Hued was the highest (692 kg/ha) at Bembeke. Strong positive correlations between seed yield and (1) plant height (r = 0.74), (2) days to maturity (r = 0.76), and (3) biomass (r = 0.87) were found under irrigated conditions. The rainfed evaluations at Bunda revealed significant differences in seed yield, plant biomass, and seed size among the genotypes. The highest yielding genotype was Black Seeded (2050 kg/ha) followed by Multi-Hued (1603 kg/ha) and Bio-Bio (1446 kg/ha). Ecuadorian (257 kg/ha) was

  13. Prone to fix: Resilience of the active nitrogen-fixing rice root microbiome

    NASA Astrophysics Data System (ADS)

    Hurek, Thomas; Sabale, Mugdha; Sarkar, Abhijit; Pees, Tobias; Reinhold-Hurek, Barbara

    2016-04-01

    Due to water consumption, many lowland rice areas in Asia are undergoing a transition that involves adoption of new management strategies, with crop rotations encompassing a non-flooded crop, including maize. Shifting from flooded to non-flooded cropping is likely to affect microbial nitrogen cycling. For analysis of the root-associated microbiome of rice and maize in response to flooding or nitrogen fertilizer, we combine methods of microbial ecology (Next-Generation sequencing of amplicons), and a reductionist approach with pure cultures of the endophytic diazotroph Azoarus sp.. Field plots of the ICON project (Introducing non-flooded crops in rice-dominated landscapes: Impact on Carbon, nitrogen and water budgets) at the International Rice Research Institute in the Philippines were analyzed. Root-associated activity of nitrogenase gene expression was assessed by quantitative RT-PCR of nifH. For rice, expression levels were surprisingly stable, in response to non-flooded versus flooded conditions, or in response to conventional nitrogen fertilizer applications versus lack of N-fertilizer. In contrast, the active diazotrophic population of maize roots was not resistant to N-fertilization, nifH expression strongly decreased. Concordant changes in the diazotrophic resident or active communities were detected by nifH amplicon sequence analysis, based on bacterial DNA or mRNA, respectively. For high-resolution analyses of the endobiome in gnotobiotic culture, we developed a dual fluorescence reporter system for Azoarcus sp. BH72 which allows to quantify and visualize epi- and endophytic gene expression by concfocal microscopy (CLSM). This allowed us to demonstrate sites of active nitrogen fixation (gene expression) in association with rice roots. We confirmed that at low nitrogen fertilizer levels, endophytic nifH gene expression persisted in rice roots, while it was repressed in maize roots. This supports our observation of remarkable stability of nitrogen fixation

  14. Deposition by the 2011 Tohoku-oki tsunami on coastal lowland controlled by beach ridges near Sendai, Japan

    NASA Astrophysics Data System (ADS)

    Takashimizu, Yasuhiro; Urabe, Atsushi; Suzuki, Koji; Sato, Yoshiki

    2012-12-01

    A study of the 2011 Tohoku-oki tsunami deposits on the coastal lowland of the Sendai Plain, Japan was carried out along a shore-perpendicular survey line in the Arahama area. Field descriptions and tsunami water depth measurements were complemented by sedimentary analyses, including grain size, grain fabric and diatom analysis. The tsunami deposits show a generally fining-inland trend along the 3.4 km long transect. The depositional facies, grain size analysis and grain fabric data suggest that most of the tsunami deposits were laid down during the tsunami inflow, except at one site. These tsunami deposits are characterized by parallel-laminated or massive sand and silt with pieces of woods, fragments of glass, rip-up mud clasts and an erosional base. Minor backwash deposits overlying the inflow sand layer were only observed on one beach ridge and attributed to the topographic high. Marine diatom species comprised only approximately 2% of the diatom assemblage in tsunami deposits and their content decreased landward. In this study, diatom assemblages were similar in the rice field soil and tsunami layers, suggesting that the muddy fraction of the deposits mainly consists of sediments derived from the tsunami-eroded rice field soil. As a result of soil erosion, the tsunami had a high suspended sediment load. Furthermore, after the first tsunami inundation, seawater left by the tsunami did not drain completely to the sea because of the high coastal beach ridge and/or coastal subsidence due to the massive earthquake. Therefore, strong tsunami outflows to the sea did not occur and these areas were covered by mud deposited from stagnant water.

  15. Iron absorption from brown rice/brown rice-based meal and milled rice/milled rice-based meal.

    PubMed

    Trinidad, Trinidad P; Mallillin, Aida C; Sagum, Rosario S; Briones, Dave P; Encabo, Rosario R; Juliano, Bienvenido O

    2009-12-01

    Milled rice is the staple food among Filipinos and is mostly consumed three times a day. Rice as a source of iron could therefore have an important role in the existing 37% prevalence of iron-deficiency anemia in the country. Previous iron absorption studies in Filipinos from rice and rice-based meals were carried out on milled rice but no research was done on brown rice of the same variety. This leads to the hypothesis that brown rice may be better than milled rice in terms of iron content. To determine iron absorption from brown rice and brown rice-based meal, and from milled rice and milled rice-based meal of the same variety. The rice variety used in the study was F(2) seeds of PSB Rc72H. Iron absorption from brown/milled rice and brown/milled rice-based meals was determined in 12 healthy human subjects from the incorporation of radioisotopes of iron into erythrocytes 14 days after administration of the labeled rice/rice-based meals. The above samples were also analyzed for nutrient content, including dietary fiber, and iron. The iron content of brown rice was significantly higher (1.1 +/- 0.1 mg/100 g) than that of milled rice (0.6 +/- 0.1 mg/100 g). Brown rice has significantly greater amounts of total dietary fiber (5.4 +/- 0.4%) than milled rice (1.7 +/- 0.2%; P < 0.05). Both tannic acid and phytic acid contents in brown rice (56.9 +/- 3.2 mg/100 g and 290.1 +/- 18.0 mg/100 g, respectively) were significantly higher than those of milled rice (21.3 +/- 2.3 mg/100 g and 84.0 +/- 12.4 mg/100 g, respectively; P<0.05). The amount of iron absorbed from brown rice (0.13 +/- 0.02 mg) did not differ significantly from that from milled rice (0.14 +/- 0.02 mg). However, the amount from brown rice-based meal (0.36 +/- 0.04 mg) differed significantly from that from brown rice (P<0.05) as well as that from milled rice-based meal (0.35 +/- 0.03 mg) from that from milled rice (P<0.05). Moreover, brown rice-based meal did not differ significantly from milled rice-based meal

  16. Fire and flood management of coastal swamp enabled first rice paddy cultivation in east China.

    PubMed

    Zong, Y; Chen, Z; Innes, J B; Chen, C; Wang, Z; Wang, H

    2007-09-27

    The adoption of cereal cultivation was one of the most important cultural processes in history, marking the transition from hunting and gathering by Mesolithic foragers to the food-producing economy of Neolithic farmers. In the Lower Yangtze region of China, a centre of rice domestication, the timing and system of initial rice cultivation remain unclear. Here we report detailed evidence from Kuahuqiao that reveals the precise cultural and environmental context of rice cultivation at this earliest known Neolithic site in eastern China, 7,700 calibrated years before present (cal. yr bp). Pollen, algal, fungal spore and micro-charcoal data from sediments demonstrate that these Neolithic communities selected lowland swamps for their rice cultivation and settlement, using fire to clear alder-dominated wetland scrub and prepare the site for occupation, then to maintain wet grassland vegetation of paddy type. Regular flooding by slightly brackish water was probably controlled by 'bunding' to maintain crop yields. The site's exploitation ceased when it was overwhelmed by marine inundation 7,550 cal. yr bp. Our results establish that rice cultivation began in coastal wetlands of eastern China, an ecosystem vulnerable to coastal change but of high fertility and productivity, attractions maximized for about two centuries by sustained high levels of cultural management of the environment.

  17. Comparing the water-use-efficiency of maize and biomass sorghum grown in the rain-fed, Midwestern US.

    NASA Astrophysics Data System (ADS)

    Roby, M.; VanLoocke, A. D.; Heaton, E.; Miguez, F.; Salas Fernandez, M.

    2015-12-01

    Uncertainty in the quantity and timing of precipitation in a changing climate, combined with an increased demand for non-grain ethanol feedstock, may necessitate expanding the production of more water-use-efficient and less drought sensitive crops for biofuel applications. Research suggests that biomass sorghum [Sorghum bicolor (L.) Moench] is more drought tolerant and can produce more biomass than maize in water-limiting environments; however, sorghum water use data are scarce for the rain-fed Midwestern US. To address this gap, a replicated (n=3) side-by-side trial was established in Ames, Iowa to determine cumulative water use and water-use-efficiency of maize and biomass sorghum throughout the 2014 and 2015 growing seasons. Latent heat flux was estimated using the residual in the energy balance technique. Continuous micrometeorological measurements were supplemented by periodic measurements of leaf area index (LAI) and above-ground biomass. Water use (WU), aboveground biomass, and water-use-efficiency (WUE) were found to be similar for both crop types in 2014; data from the 2015 growing season are currently being processed. In 2015, leaf gas exchange measurements were made with a portable photosynthesis instrument. Photosynthetic parameters from gas exchange measurements will be implemented in a semi-mechanistic crop model (BioCro) as a method for scaling WUE estimates across the rain-fed Midwestern US driven with future climate projections. This research highlights the importance of understanding the potential effects of expanding biomass sorghum production on the hydrologic cycle of the Midwestern, US.

  18. Land, Water and Society in the Maya Lowlands

    NASA Astrophysics Data System (ADS)

    Murtha, T.; French, K.; Duffy, C.; Webster, D.

    2013-12-01

    This paper reports the results of our project investigating the long-term spatial and temporal dynamics of land use management, agricultural decision-making and patterns of resource availability in the tropical lowlands of Central America. Overall, our project combines diachronic environmental simulation with historic settlement pattern survey to address a series of long-standing questions about the coupled natural and human (CNH) landscape history in the Central Maya lowlands (at the UNESCO world heritage site of Tikal in the Maya Biosphere Reserve). The paper describes the preliminary results of our project, including changing patterns of land, water, settlement and political history using climate, soil and hydrologic modeling and time series spatial analysis of population and settlement patterns. The critical period of the study, 1000 BC until the present, begins with dispersed settlements accompanied by widespread deforestation and soil erosion. Population size and density grows rapidly for 800 years, while deforestation and erosion rates decline; however, there is striking evidence of political evolution during this period, including the construction of monumental architecture, hieroglyphic monuments detailing wars and alliances, and the construction of a defensive earthwork feature, signaling political territories and possibly delineating natural resource boundaries. Population decline and steady reforestation followed until more recent migration into the region, which has impacted the biosphere ecology. Building on our previous research regionally and comparative research completed in Belize and Mexico, we are modeling sample periods the 3,000-year landscape history of the region, comparing land and water availability to population distributions and what we know about political history. Simulations are generated using historic climate and land use data, primarily relying on the Erosion Productivity Impact Calculator (EPIC) and the Penn State Integrated

  19. Quantification of suspended sediment transfers in a lowland agricultural catchment

    NASA Astrophysics Data System (ADS)

    Salvador-Blanes, Sebastien; Manière, Louis; Grangeon, Thomas; Cerdan, Olivier; Evrard, Olivier; Foucher, Anthony; Vandromme, Rosalie

    2017-04-01

    Lowland agricultural landscapes underwent important changes since the second half of the XXth century such as hedges removal, implementation of drainage systems, stream redesign and land reallocation. It resulted in changes in sediment transfer processes, and in widespread morphological alterations of water bodies. However, little is known about the sediment dynamics in these environments. The Louroux catchment (25 km2) is located in central France. It is a typical intensively cultivated and tile drained lowland catchment. The Xth century pond located at its outlet (52 ha) is undergoing large siltation, with a current sedimentation rate 60 fold higher than the pre-1950 period. Five monitoring stations, measuring water levels and turbidity at high frequency (15 mn and 1 mn respectively), combined with automatic samplers, were implemented in 2013. Three stations are located at the main tributaries outlets of the pond, one in a sub-catchment, and one at a tile drain outlet. 45 floods were observed during the three studied hydrological years. They occurred mostly between December and March (33 floods) and in May-June (8 floods). Specific sediment yields ranged from 0.02 to 0.38 t.ha-1.yr-1 depending on the monitoring site and the considered year. The vast majority of suspended sediment transfers occur during the winter floods. While large water volumes were also measured during spring floods, the sediment yields remained low. Suspended sediment yields present large inter-annual (ratio ranging between 2 and 6 depending on the monitoring station) and spatial variations, due to significant differences in total rainfall amounts during the winter season and variations in land use, respectively. The processes related to sediment transfers are most likely linked to soil saturation during winter despite the presence of a tile drainage network, with transfers occurring both at the soil surface and through the drainage system. While sediment transfer rates can be considered as

  20. Innate immunity in rice

    PubMed Central

    Chen, Xuewei; Ronald, Pamela C.

    2011-01-01

    Advances in studies of rice innate immunity have led to the identification and characterization of host sensors encoding receptor kinases that perceive conserved microbial signatures. The non-RD domain, a newly recognized hallmark of these receptor kinases is highly expanded in rice (Oryza sativa) compared with Arabidopsis (Arabidopsis thaliana). Researchers have also identified a diverse array of microbial effectors from bacterial and fungal pathogens that triggers immune responses upon perception. These include both, effectors that indirectly target host Nucleotide binding site/Leucine rice repeat (NBS-LRR) proteins and transcription activator-like (TAL) effectors that directly bind promoters of host genes. Here we review the recognition and signaling events that govern rice innate immunity. PMID:21602092

  1. Rice Cultivation in Northwest Italy

    NASA Image and Video Library

    2005-06-08

    The lowlands of Lombardy and Piedmont in northwest Italy are some of the most highly developed irrigation areas in the world. These views of the region were acquired on May 8, 2005, by NASA Terra spacecraft.

  2. Perspectives on secondary forest management in tropical humid lowland America.

    PubMed

    Kammesheidt, Ludwig

    2002-05-01

    Secondary forests regrowing on abandoned agricultural land constitute an important, albeit widely overlooked, component in the landscape matrix of tropical lowland America. These 'new' forest resources on private land-holdings derive either from unsustainable cattle-ranching practices of better-off farmers or are part of the crop/fallow system of resource-poor farmers. If previous land use was light, secondary forest management may offer an interesting use option to better-off farmers, providing that subsidies for stand improvement are given. Improved fallow systems using partly the successional vegetation may be a way to establish sustainable small-scale agriculture for resource-poor farmers. Given some technical and financial input, land-use systems based on secondary vegetation could play a vital role both in sustainable landscape management and biodiversity conservation.

  3. Lowland forest loss in protected areas of Indonesian Borneo.

    PubMed

    Curran, L M; Trigg, S N; McDonald, A K; Astiani, D; Hardiono, Y M; Siregar, P; Caniago, I; Kasischke, E

    2004-02-13

    The ecology of Bornean rainforests is driven by El Niño-induced droughts that trigger synchronous fruiting among trees and bursts of faunal reproduction that sustain vertebrate populations. However, many of these species- and carbon-rich ecosystems have been destroyed by logging and conversion, which increasingly threaten protected areas. Our satellite, Geographic Information System, and field-based analyses show that from 1985 to 2001, Kalimantan's protected lowland forests declined by more than 56% (>29,000 square kilometers). Even uninhabited frontier parks are logged to supply international markets. "Protected" forests have become increasingly isolated and deforested and their buffer zones degraded. Preserving the ecological integrity of Kalimantan's rainforests requires immediate transnational management.

  4. Crash and rebound of indigenous populations in lowland South America.

    PubMed

    Hamilton, Marcus J; Walker, Robert S; Kesler, Dylan C

    2014-04-01

    Lowland South America has long been a battle-ground between European colonization and indigenous survival. Initial waves of European colonization brought disease epidemics, slavery, and violence that had catastrophic impacts on indigenous cultures. In this paper we focus on the demography of 238 surviving populations in Brazil. We use longitudinal censuses from all known indigenous Brazilian societies to quantify three demographic metrics: 1) effects of European contact on indigenous populations; 2) empirical estimates of minimum viable population sizes; and 3) estimates of post-contact population growth rates. We use this information to conduct population viability analysis (PVA). Our results show that all surviving populations suffered extensive mortality during, and shortly after, contact. However, most surviving populations exhibit positive growth rates within the first decade post-contact. Our findings paint a positive demographic outlook for these indigenous populations, though long-term survival remains subject to powerful externalities, including politics, economics, and the pervasive illegal exploitation of indigenous lands.

  5. Ecological fish production in two small lowland rivers in Poland.

    PubMed

    Penczak, Tadeusz

    1981-02-01

    Estimates were made of the ecological fish production in two small lowland rivers uninhabited by salmonids. Eight sites were examined in the Utrata River drainage basin, and five in the Zalewka Brook. Nets were placed at the upper and lower limits of each site and fish were captured using electrofishing apparatus; at the four sites estimates of fish density were verified by the use of rotenone. Twelfe fish species were found, the following being dominant: Three-spined Stickleback, Gasterosteus aculeatus L., Loach, Nemachilus barbatulus (L.), Gudgeon, Gobio gobio (L.). Ecological fish production ranged from 30.7 to 807.2 kg ha(-1) a(-1) (mean: 210.9 kg ha(-1) a(-1)). Production was highest at the sites with the lowest number of species, the maximum value occurring in the headspring section with three species.

  6. Kax and kol: collapse and resilience in lowland Maya civilization.

    PubMed

    Dunning, Nicholas P; Beach, Timothy P; Luzzadder-Beach, Sheryl

    2012-03-06

    Episodes of population loss and cultural change, including the famous Classic Collapse, punctuated the long course of Maya civilization. In many cases, these downturns in the fortunes of individual sites and entire regions included significant environmental components such as droughts or anthropogenic environmental degradation. Some afflicted areas remained depopulated for long periods, whereas others recovered more quickly. We examine the dynamics of growth and decline in several areas in the Maya Lowlands in terms of both environmental and cultural resilience and with a focus on downturns that occurred in the Terminal Preclassic (second century Common Era) and Terminal Classic (9th and 10th centuries CE) periods. This examination of available data indicates that the elevated interior areas of the Yucatán Peninsula were more susceptible to system collapse and less suitable for resilient recovery than adjacent lower-lying areas.

  7. Crash and rebound of indigenous populations in lowland South America

    NASA Astrophysics Data System (ADS)

    Hamilton, Marcus J.; Walker, Robert S.; Kesler, Dylan C.

    2014-04-01

    Lowland South America has long been a battle-ground between European colonization and indigenous survival. Initial waves of European colonization brought disease epidemics, slavery, and violence that had catastrophic impacts on indigenous cultures. In this paper we focus on the demography of 238 surviving populations in Brazil. We use longitudinal censuses from all known indigenous Brazilian societies to quantify three demographic metrics: 1) effects of European contact on indigenous populations; 2) empirical estimates of minimum viable population sizes; and 3) estimates of post-contact population growth rates. We use this information to conduct population viability analysis (PVA). Our results show that all surviving populations suffered extensive mortality during, and shortly after, contact. However, most surviving populations exhibit positive growth rates within the first decade post-contact. Our findings paint a positive demographic outlook for these indigenous populations, though long-term survival remains subject to powerful externalities, including politics, economics, and the pervasive illegal exploitation of indigenous lands.

  8. Kax and kol: Collapse and resilience in lowland Maya civilization

    PubMed Central

    Dunning, Nicholas P.; Beach, Timothy P.; Luzzadder-Beach, Sheryl

    2012-01-01

    Episodes of population loss and cultural change, including the famous Classic Collapse, punctuated the long course of Maya civilization. In many cases, these downturns in the fortunes of individual sites and entire regions included significant environmental components such as droughts or anthropogenic environmental degradation. Some afflicted areas remained depopulated for long periods, whereas others recovered more quickly. We examine the dynamics of growth and decline in several areas in the Maya Lowlands in terms of both environmental and cultural resilience and with a focus on downturns that occurred in the Terminal Preclassic (second century Common Era) and Terminal Classic (9th and 10th centuries CE) periods. This examination of available data indicates that the elevated interior areas of the Yucatán Peninsula were more susceptible to system collapse and less suitable for resilient recovery than adjacent lower-lying areas. PMID:22371571

  9. Comparison of leaf anatomy on some Nepenthes spp. (Nepenthaceae) from highland and lowland habitat in Indonesia

    NASA Astrophysics Data System (ADS)

    Arimy, N. Q.; Nisyawati, Metusala, D.

    2017-07-01

    Nepenthes (Nepenthaceae) is one of the unique plants with pitcher to absorb nutritional needs. This dicotyledonous plant is able to live in the lowland and highland. The difference of their habitat may influence its anatomical structures, such in leaves. This study aimed to compare the anatomy of lowland and highland Nepenthes leaves. We examined Nepenthes rafflesiana and N. mirabilis from the group of lowland Nepenthes. We also examined Nepenthes aristolochioides and N. singalana from the group of highland Nepenthes. Each species was represented by three adult leaves from 1-3 individual plants. Each leaf was made transverse section by using a hand mini microtome and the paradermal section was made by leaf screaping technique. Paradermal and the transverse section were dehydrated by using graded series of alcohol. Transverse section was stained with safranin 1 % and fastgreen 1 %, while the paradermal section with safranin 1 %. Microscopic observations were performed at Bioimaging Laboratory, Universitas Indonesia, Depok using a light microscope. The results showed there are differences in the anatomy structure between these two habitats. Highland Nepenthes has thicker and larger hypodermis than lowland Nepenthes. Cuticle layer in the highland Nepenthes was thicker than the lowland Nepenthes. Nectary gland on the highland Nepenthes was thicker and larger than the lowland Nepenthes. In addition, highland Nepenthes has bigger and fewer stomata density than the lowland Nepenthes.

  10. A late Holocene tephrochronology for the Maya Lowlands, Central America

    NASA Astrophysics Data System (ADS)

    Nooren, K.; Huizinga, A.; Hoek, W.; Bergen, M. V.; Middelkoop, H.

    2012-12-01

    The Maya Lowlands in southern Mexico, Guatemala and Belize were densely populated for thousands of years, and have been the subject of intensive studies on the interaction between humans and their environment. Accurate radiocarbon dating of proxy records and disrupting events has proved to be difficult due to the lack of organic material in many deposits and the 'old carbon effect' related to the calcareous geology of the Yucatan Peninsula. So far, tephrostratigraphy has hardly been used to define time markers for palynological, limnological and archaeological studies in this region, despite the frequent occurrence of tephra fall. With the objective to fill this gap, we developed a tephrochronology for the Maya Lowlands using sediment cores from a flood basin of the Usumacinta-Grijalva delta in southern Mexico. Tephrostratigraphy and radiocarbon dating were used to estimate the timing of past volcanic eruptions, and chemical compositions of glass shards were used to identify potential sources. At least six tephralayers were deposited since 2000 BC, the most notable representing eruptions of El Chichón volcano in the 5th and 15th century AD. The high sulphur emissions accompanying El Chichón's eruptions allowed testing of our age-depth model through a correlation with volcanic sulphate peaks in ice cores from Greenland and Antarctica. We demonstrate the applicability of the established tephrochronological framework in a detailed chronological reconstruction of the formation of the world's largest late Holocene beach ridge plain in southern Mexico. This plain with over 500 beach ridges is a highly sensitive recorder of combined sea level rise, subsidence, storm activity and changes in climate and upstream land use since the dawn of Olmec and Maya cultures circa 5000 years ago.

  11. Assessment of Predictability of Philippine Rice Production with Climate Information

    NASA Astrophysics Data System (ADS)

    Koide, N.; Robertson, A. W.; Qian, J.; Ines, A. M.

    2010-12-01

    El Niño Southern Oscillation is the most influential factor on the Philippine climate and has measurable impacts on rice production. The previous studies suggested potential of climate information for prediction of the rice production. For example, Roberts et al. (2009) showed the statistically significant relationship of dry-season rice production in Luzon with Niño sea surface temperature anomalies (SSTA) averaged over the Niño 3.4 region (5°N-5°S, 120°-170°W) for July to September of the year before the harvest. However, the predictive skills of climate information for rice production have not been previously analyzed yet. Thus, we have conducted the assessment of predictive skills of one uncoupled general circulation models (GCMs) (ECHAM-CA) and two coupled GCMs (ECHAM-MOM, and ECHAM-CFS), as well as those of Niño 3.4 SSTAs and the volume of water warmer than 20°C (WWV) in the equatorial Pacific Ocean (5°N-5°S, 120°E to 80°W), based on cross validation with MLR, PCR, CCA. The result clearly shows high potential of these climate information as a tool for prediction of rice production with sufficient lead time for decision makers. Detailed results are as below. Dry Season Dry season rice production of the Philippines of both irrigation and rainfed systems significantly depend on rainfall in OND of the year before the harvest (same results were found by Roberts et al. (2009)). Two coupled GCMs have high predictive skills for dry-season rice production of the Philippines with six months lead time (six months before the beginning of the harvest). In addition, we found that WWV plus zonal wind anomalies over an equatorial west Pacific also has similar predictive skills to those of these coupled GCMs. On the other hand, the uncoupled GCM has high predictive skills only with a few months lead time similar to predictive skills of Niño 3.4 SSTAs. Predictive skills at regional levels are generally lower than that for the Philippines. Many regions in Mindanao

  12. Validating Ancient Age of the Buried Floor of the Northern Lowlands, Mars

    NASA Technical Reports Server (NTRS)

    Buczkowski, D. L.; Frey, H. V.; Roark, J. H.; McGill, G. E.

    2004-01-01

    Hesperian and Amazonian plains units cover the northern lowlands but little is known about what this surface covers. Models for the creation of the lowlands and the dichotomy boundary implement mechanisms which vary from internal processes, such as plate tectonics or first-order mantle convection, to external processes, such as a single large impact or multiple impacts. Different models require different time scales for low-land formation; determining the age of the buried low-land surface would help constrain the formation models. The Mars Orbiting Laser Altimeter (MOLA) has yielded a high-precision, topographic gridded data set that reveals the presence of Quasi-Circular Depressions (QCDs) in both the southern highlands and the northern lowlands. Most of these roughly circular depressions have no corresponding visible structural feature on the surface. It is proposed that these QCDs are the surface representation of buried impact craters. Based on this assumption, cumulative number vs. diameter curves were constructed, which placed the age of the buried surface of the northern lowlands in the Early or pre-Noachian. A Noachian basement is supported by the remnants of large craters and multi-ring basins discovered in earlier research, but the QCDs provide the first evidence of this for the entire lowland. Constraining the age of the basement floor to the earliest Noachian, however, would require that the process that formed the northern lowlands either occurred in the early Noachian or involves removal of material from the bottom of the crust without destroying the previously formed craters to achieve the modeled crustal thinning. But can we establish that the QCDs do in fact represent buried impact craters, and thus validate an Early Noachian age for the buried lowland floor?

  13. Biochemical and physiological responses of rice (Oryza sativa L.) as influenced by Trichoderma harzianum under drought stress.

    PubMed

    Shukla, Nandani; Awasthi, R P; Rawat, Laxmi; Kumar, J

    2012-05-01

    Rice is one of the most important food crops drastically affected by drought in lowland rice ecosystems. In the present study, the impact of drought tolerant isolates of endophytic fungus Trichoderma harzianum on rice response to drought was investigated. Out of 43 Trichoderma isolates studied, only five isolates viz., Th 56, Th 69, Th 75, Th 82 and Th 89 were selected to be drought tolerant as these were able to colonize well on cow dung at low moisture content of 10-20 percent, though two isolates, Th 56 and Th 75, grew even at 5 percent moisture content. Trichoderma-colonized rice seedlings were slower to wilt in response to drought. Colonization delayed drought induced changes like stomatal conductance, net photosynthesis and leaf greenness. Drought conditions varying from 3 to 9 days of withholding water led to an increase in the concentration of many stress induced metabolites in rice leaves and decrease of MSI, while Trichoderma colonization caused a decrease in proline, MDA and H₂O₂ contents, and increase in phenolics concentration and MSI. Among test isolates, Th 56 induced maximum drought tolerance as treated plants recorded only 20-40 percent wilting even at 9 DDS. With or without exposure to drought, colonization by Trichoderma promoted seedling growth, with Th 56 giving the most consistent effect. The primary direct effect of Trichoderma colonization was promotion of root growth, regardless of water status, which caused delay in the drought responses of rice plants.

  14. Seasat synthetic aperture radar ( SAR) response to lowland vegetation types in eastern Maryland and Virginia.

    USGS Publications Warehouse

    Krohn, M.D.; Milton, N.M.; Segal, D.B.

    1983-01-01

    Examination of Seasat SAR images of eastern Maryland and Virginia reveals botanical distinctions between vegetated lowland areas and adjacent upland areas. Radar returns from the lowland areas can be either brighter or darker than returns from the upland forests. Scattering models and scatterometer measurements predict an increase of 6 dB in backscatter from vegetation over standing water. This agrees with the 30-digital number (DN) increase observed in the digital Seasat data. The density, morphology, and relative geometry of the lowland vegetation with respect to standing water can all affect the strength of the return L band signal.-from Authors

  15. Lake Tapps tephra: An early Pleistocene stratigraphic marker in the Puget Lowland, Washington

    USGS Publications Warehouse

    Westgate, J.A.; Easterbrook, D.J.; Naeser, N.D.; Carson, R.J.

    1987-01-01

    The rhyolitic Lake Tapps tephra was deposited about 1.0 myr ago, shortly after culmination of the early phase of the Salmon Springs Glaciation in the Puget Lowland. It is contained within sediments that were deposited in ponds or lakes in front of the reteating glacier. An herb-dominated tundra existed in the southern Puget Lowland at that time. Lake Tapps tephra is most likely the product of an eruption that in part was phreatomagmatic. It forms an early Pleistocene stratigraphic marker across the southern sector of the Puget Lowland and provides a link between Puget lobe sediments of the Cordilleran Ice Sheet and sediments deposited by Olympic alpine glaciers. ?? 1987.

  16. Regional Studies of Highland-Lowland Age Differences Across the Mars Crustal Dichotomy Boundary

    NASA Technical Reports Server (NTRS)

    Frey, H. V.; DeSoto, G. E.; Lazrus, R. M.

    2005-01-01

    Regional differences in crater retention ages (CRAs) across the Mars dichotomy boundary are compared to the global highland-lowland age difference previously determined from visible and buried impact basins based on MOLA-derived Quasi-Circular Depressions (QCDs). Here Western Arabia (WA) is compared with Ismenius Lacus (IL). We find the buried lowlands in the two regions have total CRAs essentially identical to the global average. Even more intriguing, the WA cratered terrain appears to have a CRA like that of the adjacent buried lowlands,

  17. Climatic impact of tropical lowland deforestation on nearby montane cloud forests.

    PubMed

    Lawton, R O; Nair, U S; Pielke Sr, R A; Welch, R M

    2001-10-19

    Tropical montane cloud forests (TMCFs) depend on predictable, frequent, and prolonged immersion in cloud. Clearing upwind lowland forest alters surface energy budgets in ways that influence dry season cloud fields and thus the TMCF environment. Landsat and Geostationary Operational Environmental Satellite imagery show that deforested areas of Costa Rica's Caribbean lowlands remain relatively cloud-free when forested regions have well-developed dry season cumulus cloud fields. Further, regional atmospheric simulations show that cloud base heights are higher over pasture than over tropical forest areas under reasonable dry season conditions. These results suggest that land use in tropical lowlands has serious impacts on ecosystems in adjacent mountains.

  18. Genome-wide haplotype changes produced by artificial selection during modern rice breeding in Japan.

    PubMed

    Yonemaru, Jun-ichi; Yamamoto, Toshio; Ebana, Kaworu; Yamamoto, Eiji; Nagasaki, Hideki; Shibaya, Taeko; Yano, Masahiro

    2012-01-01

    During the last 90 years, the breeding of rice has delivered cultivars with improved agronomic and economic characteristics. Crossing of different lines and successive artificial selection of progeny based on their phenotypes have changed the chromosomal constitution of the ancestors of modern rice; however, the nature of these changes is unclear. The recent accumulation of data for genome-wide single-nucleotide polymorphisms (SNPs) in rice has allowed us to investigate the change in haplotype structure and composition. To assess the impact of these changes during modern breeding, we studied 177 Japanese rice accessions, which were categorized into three groups: landraces, improved cultivars developed from 1931 to 1974 (the early breeding phase), and improved cultivars developed from 1975 to 2005 (the late breeding phase). Phylogenetic tree and structure analysis indicated genetic differentiation between non-irrigated (upland) and irrigated (lowland) rice groups as well as genetic structuring within the irrigated rice group that corresponded to the existence of three subgroups. Pedigree analysis revealed that a limited number of landraces and cultivars was used for breeding at the beginning of the period of systematic breeding and that 11 landraces accounted for 70% of the ancestors of the modern improved cultivars. The values for linkage disequilibrium estimated from SNP alleles and the haplotype diversity determined from consecutive alleles in five-SNP windows indicated that haplotype blocks became less diverse over time as a result of the breeding process. A decrease in haplotype diversity, caused by a reduced number of polymorphisms in the haplotype blocks, was observed in several chromosomal regions. However, our results also indicate that new haplotype polymorphisms have been generated across the genome during the breeding process. These findings will facilitate our understanding of the association between particular haplotypes and desirable phenotypes in

  19. Research priorities for rice pest management in tropical Asia: a simulation analysis of yield losses and management efficiencies.

    PubMed

    Willocquet, Laetitia; Elazegui, Francisco A; Castilla, Nancy; Fernandez, Luzviminda; Fischer, Kenneth S; Peng, Shaobing; Teng, Paul S; Srivastava, R K; Singh, H M; Zhu, Defeng; Savary, Serge

    2004-07-01

    ABSTRACT A simulation study was conducted to assess the current and prospective efficiency of rice pest management and develop research priorities for lowland production situations in tropical Asia. Simulation modeling with the RICEPEST model provided the flexibility required to address varying production situations and diverse pest profiles (bacterial leaf blight, sheath blight, brown spot, leaf blast, neck blast, sheath rot, white heads, dead hearts, brown plant-hoppers, insect defoliators, and weeds). Operational definitions for management efficacy (injury reduction) and management efficiency (yield gain) were developed. This approach enabled the modeling of scenarios pertaining to different pest management strategies within the agroecological contexts of rice production and their associated pest injuries. Rice pests could be classified into two broad research priority-setting categories with respect to simulated yield losses and management efficiencies. One group, including weeds, sheath blight, and brown spot, consists of pests for which effective pest management tools need to be developed. The second group consists of leaf blast, neck blast, bacterial leaf blight, and brown plant-hoppers, for which the efficiency of current management methods is to be maintained. Simulated yield losses in future production situations indicated that a new type of rice plant with high-harvest index and high-biomass production ("New Plant Type") was more vulnerable to pests than hybrid rice. Simulations also indicated that the impact of deployment of host resistance (e.g., through genetic engineering) was much larger when targeted against sheath blight than when targeted against stem borers. Simulated yield losses for combinations of production situations and injury profiles that dominate current lowland rice production in tropical Asia ranged from 140 to 230 g m(-2). For these combinations, the simulated efficiency of current pest management methods, expressed in terms of

  20. Red Yeast Rice: An Introduction

    MedlinePlus

    ... help lower blood levels of cholesterol and related lipids. Red yeast rice products may not be safe; ... to lower blood levels of cholesterol and related lipids. Some red yeast rice products contain substances called ...

  1. Shaping a better rice plant.

    PubMed

    Springer, Nathan

    2010-06-01

    Two studies describe how regulatory variation at the rice gene OsSPL14 can lead to altered plant morphology and improve grain yield. These studies support the possibility of improving rice yield through changing plant architecture.

  2. 7 CFR 868.310 - Grades and grade requirements for the classes Long Grain Milled Rice, Medium Grain Milled Rice...

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... Grain Milled Rice, Medium Grain Milled Rice, Short Grain Milled Rice, and Mixed Milled Rice. (See also Â... Milled Rice Principles Governing Application of Standards § 868.310 Grades and grade requirements for the classes Long Grain Milled Rice, Medium Grain Milled Rice, Short Grain Milled Rice, and Mixed Milled Rice...

  3. 7 CFR 868.310 - Grades and grade requirements for the classes Long Grain Milled Rice, Medium Grain Milled Rice...

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... Grain Milled Rice, Medium Grain Milled Rice, Short Grain Milled Rice, and Mixed Milled Rice. (See also Â... Milled Rice Principles Governing Application of Standards § 868.310 Grades and grade requirements for the classes Long Grain Milled Rice, Medium Grain Milled Rice, Short Grain Milled Rice, and Mixed Milled Rice...

  4. 7 CFR 868.310 - Grades and grade requirements for the classes Long Grain Milled Rice, Medium Grain Milled Rice...

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... Grain Milled Rice, Medium Grain Milled Rice, Short Grain Milled Rice, and Mixed Milled Rice. (See also Â... Milled Rice Principles Governing Application of Standards § 868.310 Grades and grade requirements for the classes Long Grain Milled Rice, Medium Grain Milled Rice, Short Grain Milled Rice, and Mixed Milled Rice...

  5. Rheological properties of rice-blackgram batter while replacing white rice with brown rice.

    PubMed

    Manickavasagan, Annamalai; Al-Marhubi, Insaaf Mohd; Dev, Satyanarayan

    2014-06-01

    Rice-blackgram batter is a raw material for many traditional convenience foods in Asia. Reformulation of traditional convenience food by replacing white rice with whole rice (brown rice) is a novel method to reduce the consumption of refined grain and increase the intake of whole grain in our diet. In this study, rheological properties of rice-blackgram batter was investigated while replacing white rice with brown rice at five levels (T1--0% replacement (control), T2--25% replacement, T3--50% replacement, T4--75% replacement, and T5--100% replacement). The shear stress versus shear rate plot indicates that the rice-blackgram batter exhibited non-Newtonian fluid behavior (shear thinning property) even after 100% replacement of white rice with brown rice. The rheological characteristics of rice-blackgram batters fitted reasonably well in Cassan (r2 = 0.8521-0.9856) and power law (r2 = 0.8042-0.9823) models. Brown rice replacement at all levels did not affect the flow behavior index, yield stress, consistency coefficient, and apparent viscosity of batter at 25 degrees C. However, at higher temperature, the viscosity was greater for T4 and T5 (no difference between them) than T1, T2, and T3 (no difference between them) batters. Further research is required to determine the sensory attributes and acceptability of the cooked products with brown rice-blended batter.

  6. Fasciola gigantica transmission in the zoonotic fascioliasis endemic lowlands of Guilan, Iran: experimental assessment.

    PubMed

    Ashrafi, Keyhan; Mas-Coma, Santiago

    2014-09-15

    The lowland flatlands around the city of Bandar-Anzali, at the Caspian Sea shore, Guilan province, are an endemic area where Fasciola gigantica appears to be the fasciolid species involved and past outbreaks affecting around 15,000 people and the highest human infection rates in Iran have been reported. Fascioliasis transmission in that area has been experimentally analysed for the first time, by means of assays of monomiracidial (Group A: 120 snails) and pentamiracidial (Group B: 96 snails) infections of local Radix lymnaeid snails with a local cattle F. gigantica isolate. Ribosomal DNA ITS-2 sequencing proved that Lymnaea (Radix) gedrosiana should henceforth be considered a synonym of Radix auricularia, the haplotype found in Bandar-Anzali being identical to that found in many European countries. Survival rates at day 30 postinfection and metacercarial productivity (both higher in Group A) and longevity of the shedding snails (higher in Group B), were affected by the miracidial dose, whereas prepatent period, patent period, infection rate, and the percentages of shedding and infected non-shedding snails did not. The higher percentage of shedding snails in Group A (51.0% versus 37.7%) counteracts the higher number of metacercariae produced in Group B (243.9 ± 259.2 versus 157.2 ± 153.2). High numbers of shedding snails in both experimental groups passed less than 100 cercariae, and 16% in Group A and 35% in Group B produced more than 300 metacercariae, while only four snails (8%) in Group A and two snails (10%) in Group B shed more than 500 metacercariae. Most metacercariae (94.7% in Group A and 85.1% in Group B) were recorded during the first 15 days of patent period. The comparison with results from other fasciolid/lymnaeid systems indicates that the F. gigantica/R. auricularia system of Guilan is highly susceptible and compatible. Results obtained suggest that increased lymnaeid vector populations and not polymiracidial snail infections most probably underlay

  7. Hydrological behavior of a Vertisol under different soil management systems in a rain-fed olive orchard

    NASA Astrophysics Data System (ADS)

    Cabezas, Jose Manuel; Gómez, Jose Alfonso; Auxiliadora Soriano, María

    2016-04-01

    Soil water availability is a major subject in Mediterranean agricultural systems, mainly due to the limited and highly variable annual rainfall, high evaporative demand, and soil hydrological characteristics. The recent expansion of olive cultivation in the rolling-plains of the Guadalquivir valley, due to the higher profitability of new intensive olive orchards, expanded the presence of olive orchards on Vertisols, soils traditionally used for annual rain-fed crops. These soils have a high content of smectitic clays, which give them a high water storage capacity, and are characterized by vertical and deep shrinkage cracks in the dry season, associated to low soil moisture. Farmers make several tillage passes in these olive groves during the summer, in order to cover the cracks and thus reduce soil water loss by evaporation, which will impact especially in rain-fed in the next olive yield. This tillage practice involves removal of plant residues from the soil surface, as well as burying seeds produced by the plants, so this will remain bared at the beginning of the rainy season, when in the Mediterranean climate is frequent occurrence of high-intensity rainfall, which are ideal conditions for soil loss by water erosion, one of the most serious problems for the sustainability of olive cultivation in Andalusia. Although there are some studies showing that water loss by evaporation from deep horizons of a vertic soil might be elevated (eg. Ritchie and Adams, 1974), the presence of plant residues on the soil surface drastically reduced soil water loss (eg Adams et al., 1969). Thus the aim of this study was to assess of soil moisture dynamics in a rain-fed olive orchard growing on a Vertisol under different soil management practices, in Andalusia (southern Spain). Four different soil management treatments were applied, which combined a cover crop (Bromus rubens L.) or bare soil throughout the year by applying herbicides, with tillage in summer to cover the cracks or non

  8. Early ceremonial constructions at Ceibal, Guatemala, and the origins of lowland Maya civilization.

    PubMed

    Inomata, Takeshi; Triadan, Daniela; Aoyama, Kazuo; Castillo, Victor; Yonenobu, Hitoshi

    2013-04-26

    The spread of plaza-pyramid complexes across southern Mesoamerica during the early Middle Preclassic period (1000 to 700 BCE) provides critical information regarding the origins of lowland Maya civilization and the role of the Gulf Coast Olmec. Recent excavations at the Maya site of Ceibal, Guatemala, documented the growth of a formal ceremonial space into a plaza-pyramid complex that predated comparable buildings at other lowland Maya sites and major occupations at the Olmec center of La Venta. The development of lowland Maya civilization did not result from one-directional influence from La Venta, but from interregional interactions, involving groups in the southwestern Maya lowlands, Chiapas, the Pacific Coast, and the southern Gulf Coast.

  9. Combining Limited Multiple Environment Trials Data with Crop Modeling to Identify Widely Adaptable Rice Varieties

    PubMed Central

    Li, Tao; Ali, Jauhar; Franje, Neil Johann; Revilleza, Jastin Edrian; Redoña, Edilberto; Xu, Jianlong

    2016-01-01

    Multi-Environment Trials (MET) are conventionally used to evaluate varietal performance prior to national yield trials, but the accuracy of MET is constrained by the number of test environments. A modeling approach was innovated to evaluate varietal performance in a large number of environments using the rice model ORYZA (v3). Modeled yields representing genotype by environment interactions were used to classify the target population of environments (TPE) and analyze varietal yield and yield stability. Eight Green Super Rice (GSR) and three check varieties were evaluated across 3796 environments and 14 seasons in Southern Asia. Based on drought stress imposed on rainfed rice, environments were classified into nine TPEs. Relative to the check varieties, all GSR varieties performed well except GSR-IR1-5-S14-S2-Y2, with GSR-IR1-1-Y4-Y1, and GSR-IR1-8-S6-S3-Y2 consistently performing better in all TPEs. Varietal evaluation using ORYZA (v3) significantly corresponded to the evaluation based on actual MET data within specific sites, but not with considerably larger environments. ORYZA-based evaluation demonstrated the advantage of GSR varieties in diverse environments. This study substantiated that the modeling approach could be an effective, reliable, and advanced approach to complement MET in the assessment of varietal performance on spatial and temporal scales whenever quality soil and weather information are accessible. With available local weather and soil information, this approach can also be adopted to other rice producing domains or other crops using appropriate crop models. PMID:27723774

  10. Combining Limited Multiple Environment Trials Data with Crop Modeling to Identify Widely Adaptable Rice Varieties.

    PubMed

    Li, Tao; Ali, Jauhar; Marcaida, Manuel; Angeles, Olivyn; Franje, Neil Johann; Revilleza, Jastin Edrian; Manalo, Emmali; Redoña, Edilberto; Xu, Jianlong; Li, Zhikang

    2016-01-01

    Multi-Environment Trials (MET) are conventionally used to evaluate varietal performance prior to national yield trials, but the accuracy of MET is constrained by the number of test environments. A modeling approach was innovated to evaluate varietal performance in a large number of environments using the rice model ORYZA (v3). Modeled yields representing genotype by environment interactions were used to classify the target population of environments (TPE) and analyze varietal yield and yield stability. Eight Green Super Rice (GSR) and three check varieties were evaluated across 3796 environments and 14 seasons in Southern Asia. Based on drought stress imposed on rainfed rice, environments were classified into nine TPEs. Relative to the check varieties, all GSR varieties performed well except GSR-IR1-5-S14-S2-Y2, with GSR-IR1-1-Y4-Y1, and GSR-IR1-8-S6-S3-Y2 consistently performing better in all TPEs. Varietal evaluation using ORYZA (v3) significantly corresponded to the evaluation based on actual MET data within specific sites, but not with considerably larger environments. ORYZA-based evaluation demonstrated the advantage of GSR varieties in diverse environments. This study substantiated that the modeling approach could be an effective, reliable, and advanced approach to complement MET in the assessment of varietal performance on spatial and temporal scales whenever quality soil and weather information are accessible. With available local weather and soil information, this approach can also be adopted to other rice producing domains or other crops using appropriate crop models.

  11. Cervical necrotizing fasciitis and myositis in a western lowland gorilla (Gorilla gorilla gorilla).

    PubMed

    Allender, M C; McCain, S L; Ramsay, E C; Schumacher, J; Ilha, M R S

    2009-06-01

    A 39-yr-old wild-caught, female western lowland gorilla (Gorilla gorilla gorilla) died during an immobilization to assess swelling and apparent pain of the cervical region. Necropsy revealed a fistulous tract containing plant material in the oropharynx, above the soft palate, communicating with a left-sided cervical necrotizing fasciitis and myositis. Alpha-hemolytic Streptococcus and Prevotella sp. were isolated from the cervical lesion. This is a report of cervical necrotizing fasciitis in a western lowland gorilla.

  12. Herpetofauna of lowland bottomlands of southeastern Arizona: a comparison of sites

    Treesearch

    Philip C. Rosen; William R. Radke; Dennis J. Caldwell

    2005-01-01

    We intensively sampled the riparian herpetofauna at three sites in southeastern Arizona, a canyon site, Leslie Canyon, and two lowland sites, San Bernardino NWR and Empire-Ci¨¦nega Creek at Las Ci¨¦negas National Conservation Area. We also compiled a list of herpetofaunal records for the original lowland riparian area at Tucson using museum records. The herpetofaunas...

  13. Mars Crustal Dichotomy: Large Lowland Impact Basins may have Formed in Pre-Thinned Crust

    NASA Technical Reports Server (NTRS)

    Frey, H. V.

    2008-01-01

    Crater retention ages of large impact basins on Mars suggest most formed in a relatively short time, perhaps in less than 200 million years. Large basins in the lowlands have thinner central regions than similar size basins in the highlands. Large lowland impact basins, which we previously suggested might explain the low topography and thin crust of the northern part of Mars, may have formed in crust already thinned by yet earlier processes.

  14. Development of pre-breeding technology for root system study and selection of Kihara Afghan wheat landraces (KAWLR) to enhance wheat breeding in the rain-fed region

    PubMed Central

    Haque, Emdadul; Osmani, Aziz Ahmad; Ahmadi, Sayed Hasibullah; Ban, Tomohiro

    2016-01-01

    To enhance a root trait-based selection program for rain-fed wheat breeding in Afghanistan, we simulated an efficient pre-breeding drought system. Plants were grown in 1 m pipes as control or 2 m pipes to simulate drought conditions soaking ground water up by capillary action supplemented by two different life supporting irrigations from top of the pipes (T1 and T2 droughts). T1 was used for studying genetic diversity in 360 Kihara Afghan wheat landraces (KAWLR). Both drought treatments were used to evaluate root traits in 30 selected genotypes. KAWLR showed large root length variations under T1, categorized as long root (>200 cm; LR), medium root (100–150 cm; MR) and short root (20–100 cm; SR) systems. LR genotypes were more drought resistant in terms of greater plant survivability under T1 and T2 compared with other groups and were capable of adjusting their root biomass partitioning at deepest part of the soil profile. Majority of the LR genotypes originated from predominantly rain-fed provinces, and most of their agronomic traits were strongly correlated with root biomass deep in the soil in response to drought. Three LR genotypes, including the longest root genotype LR-871 (KU7604), are recommended for rain-fed wheat breeding in Afghanistan. PMID:28163597

  15. Development of pre-breeding technology for root system study and selection of Kihara Afghan wheat landraces (KAWLR) to enhance wheat breeding in the rain-fed region.

    PubMed

    Haque, Emdadul; Osmani, Aziz Ahmad; Ahmadi, Sayed Hasibullah; Ban, Tomohiro

    2016-12-01

    To enhance a root trait-based selection program for rain-fed wheat breeding in Afghanistan, we simulated an efficient pre-breeding drought system. Plants were grown in 1 m pipes as control or 2 m pipes to simulate drought conditions soaking ground water up by capillary action supplemented by two different life supporting irrigations from top of the pipes (T1 and T2 droughts). T1 was used for studying genetic diversity in 360 Kihara Afghan wheat landraces (KAWLR). Both drought treatments were used to evaluate root traits in 30 selected genotypes. KAWLR showed large root length variations under T1, categorized as long root (>200 cm; LR), medium root (100-150 cm; MR) and short root (20-100 cm; SR) systems. LR genotypes were more drought resistant in terms of greater plant survivability under T1 and T2 compared with other groups and were capable of adjusting their root biomass partitioning at deepest part of the soil profile. Majority of the LR genotypes originated from predominantly rain-fed provinces, and most of their agronomic traits were strongly correlated with root biomass deep in the soil in response to drought. Three LR genotypes, including the longest root genotype LR-871 (KU7604), are recommended for rain-fed wheat breeding in Afghanistan.

  16. Duration and Frequency Analysis of Lowland Flooding in Western Murfreesboro, Rutherford County, Tennessee, 1998-2000

    USGS Publications Warehouse

    Law, George S.

    2002-01-01

    Periodic flooding occurs at lowlands and sinkholes in and adjacent to the flood plain of the West Fork Stones River in the western part of Murfreesboro, Tennessee. Flooding in this area commonly occurs during the winter months from December through March. The maximum water level that flood waters will reach in a lowland or sinkhole is controlled by the elevation of the land surrounding the site or the overflow outlet. Maximum water levels, independent of overflow from the river, were estimated to be reached in lowlands and sinkholes in the study area every 1 to 4 years. Minor overflow from the West Fork Stones River (less than 1 foot in depth) into the study area has been estimated to occur every 10 to 20 years. Moderate overflow from the river (1 to 2 feet in depth) occurs on average every 20 to 50 years, while major river overflow (in excess of 2 feet in depth) can be expected every 50 years. Rainfall information for the area, and streamflow and water-level measurements from the West Fork Stones River, lowlands, sinkholes, caves, and wells in the study area were used to develop a flood-prone area map, independent of overflow from the river, for the study area. Water-level duration and frequency relations, independent of overflow from the river, were estimated for several lowlands, sinkholes, and wells in the study area. These relations are used to characterize flooding in lowland areas of western Murfreesboro, Rutherford County, Tennessee.

  17. Western lowland gorillas (Gorilla gorilla gorilla) change their activity patterns in response to frugivory.

    PubMed

    Masi, Shelly; Cipolletta, Chloé; Robbins, Martha M

    2009-02-01

    The most important environmental factor explaining interspecies variation in ecology and sociality of the great apes is likely to be variation in resource availability. Relatively little is known about the activity patterns of western lowland gorillas (Gorilla gorilla gorilla), which inhabit a dramatically different environment from the well-studied mountain gorillas (G. beringei beringei). This study aims to provide a detailed quantification of western lowland gorillas' activity budgets using direct observations on one habituated group in Bai Hokou, Central African Republic. We examined how activity patterns of both sexes are shaped by seasonal frugivory. Activity was recorded with 5-min instantaneous sampling between December 2004 and December 2005. During the high-frugivory period the gorillas spent less time feeding and more time traveling than during the low-frugivory period. The silverback spent less time feeding but more time resting than both females and immatures, which likely results from a combination of social and physiological factors. When compared with mountain gorillas, western lowland gorillas spend more time feeding (67 vs. 55%) and traveling (12 vs. 6.5%), but less time resting (21 vs. 34%) and engaging in social/other activities (0.5 vs. 3.6%). This disparity in activity budgets of western lowland gorillas and mountain gorillas may be explained by the more frugivorous diet and the greater dispersion of food resources experienced by western lowland gorillas. Like other apes, western lowland gorillas change their activity patterns in response to changes in the diet.

  18. Dissecting maize diversity in lowland South America: genetic structure and geographic distribution models.

    PubMed

    Bracco, Mariana; Cascales, Jimena; Hernández, Julián Cámara; Poggio, Lidia; Gottlieb, Alexandra M; Lia, Verónica V

    2016-08-26

    Maize landraces from South America have traditionally been assigned to two main categories: Andean and Tropical Lowland germplasm. However, the genetic structure and affiliations of the lowland gene pools have been difficult to assess due to limited sampling and the lack of comparative analysis. Here, we examined SSR and Adh2 sequence variation in a diverse sample of maize landraces from lowland middle South America, and performed a comprehensive integrative analysis of population structure and diversity including already published data of archaeological and extant specimens from the Americas. Geographic distribution models were used to explore the relationship between environmental factors and the observed genetic structure. Bayesian and multivariate analyses of population structure showed the existence of two previously overlooked lowland gene pools associated with Guaraní indigenous communities of middle South America. The singularity of this germplasm was also evidenced by the frequency distribution of microsatellite repeat motifs of the Adh2 locus and the distinct spatial pattern inferred from geographic distribution models. Our results challenge the prevailing view that lowland middle South America is just a contact zone between Andean and Tropical Lowland germplasm and highlight the occurrence of a unique, locally adapted gene pool. This information is relevant for the conservation and utilization of maize genetic resources, as well as for a better understanding of environment-genotype associations.

  19. Effect of rice variety and nutrient management on rice productivity in organic rice system

    USDA-ARS?s Scientific Manuscript database

    Demand for organic rice has been increasing for decades. However, the information on sustainable organic rice production systems is still lacking. The objective of this study was to investigate the effects of soil amendment products, nitrogen rate, and variety on rice grain yield, yield components, ...

  20. Methane potential and biodegradability of rice straw, rice husk and rice residues from the drying process.

    PubMed

    Contreras, L M; Schelle, H; Sebrango, C R; Pereda, I

    2012-01-01

    Agricultural solid residues are a potential renewable energy source. Rice harvesting and production in Sancti Spíritus province, Cuba, currently generates residues without an environmentally sustainable disposal route. Rice residues (rice straw, rice husk and rice residues from the drying process) are potentially an important carbon source for anaerobic digestion. For this paper, rice residues were placed for 36 days retention time in anaerobic batch reactor environments at both mesophilic (37 °C) and thermophilic (55 °C) conditions. Biogas and methane yield were determined as well as biogas composition. The results showed that rice straw as well as rice residues from the drying process had the highest biogas and methane yield. Temperature played an important role in determining both biogas yield and kinetics. In all cases, rice straw produced the highest yields; under mesophilic conditions the biogas yield was 0.43 m(3) kg(VS)(-1), under thermophilic conditions biogas yield reached 0.52 m(3) kg(VS)(-1). In the case of the rice husk, the biodegradability was very low. Methane content in all batches was kept above 55% vol. All digested material had a high carbon:nitrogen (C:N) ratio, even though significant biodegradation was recorded with the exception of rice husk. A first-order model can be used to describe the rice crop residues fermentation effectively.

  1. Mapping rice-fallow cropland areas for short-season grain legumes intensification in South Asia using MODIS 250 m time-series data

    USGS Publications Warehouse

    Gumma, Murali Krishna; Thenkabail, Prasad S.; Teluguntla, Pardhasaradhi G.; Rao, Mahesh N.; Mohammed, Irshad A.; Whitbread, Anthony M.

    2016-01-01

    The goal of this study was to map rainfed and irrigated rice-fallow cropland areas across South Asia, using MODIS 250 m time-series data and identify where the farming system may be intensified by the inclusion of a short-season crop during the fallow period. Rice-fallow cropland areas are those areas where rice is grown during the kharif growing season (June–October), followed by a fallow during the rabi season (November–February). These cropland areas are not suitable for growing rabi-season rice due to their high water needs, but are suitable for a short -season (≤3 months), low water-consuming grain legumes such as chickpea (Cicer arietinum L.), black gram, green gram, and lentils. Intensification (double-cropping) in this manner can improve smallholder farmer’s incomes and soil health via rich nitrogen-fixation legume crops as well as address food security challenges of ballooning populations without having to expand croplands. Several grain legumes, primarily chickpea, are increasingly grown across Asia as a source of income for smallholder farmers and at the same time providing rich and cheap source of protein that can improve the nutritional quality of diets in the region. The suitability of rainfed and irrigated rice-fallow croplands for grain legume cultivation across South Asia were defined by these identifiers: (a) rice crop is grown during the primary (kharif) crop growing season or during the north-west monsoon season (June–October); (b) same croplands are left fallow during the second (rabi) season or during the south-east monsoon season (November–February); and (c) ability to support low water-consuming, short-growing season (≤3 months) grain legumes (chickpea, black gram, green gram, and lentils) during rabi season. Existing irrigated or rainfed crops such as rice or wheat that were grown during kharif were not considered suitable for growing during the rabi season, because the moisture/water demand of these crops is too high. The

  2. Allele Mining and Selective Patterns of Pi9 Gene in a Set of Rice Landraces from India

    PubMed Central

    Imam, Jahangir; Mandal, Nimai P.; Variar, Mukund; Shukla, Pratyoosh

    2016-01-01

    Allelic variants of the broad-spectrum blast resistance gene, Pi9 (nucleotide binding site-leucine-rich repeat region) have been analyzed in Indian rice landraces. They were selected from the list of 338 rice landraces phenotyped in the rice blast nursery at central Rainfed Upland Rice Research Station, Hazaribag. Six of them were further selected on the basis of their resistance and susceptible pattern for virulence analysis and selective pattern study of Pi9 gene. The sequence analysis and phylogenetic study illustrated that such sequences are vastly homologous and clustered into two groups. All the blast resistance Pi9 alleles were grouped into one cluster, whereas Pi9 alleles of susceptible landraces formed another cluster even though these landraces have a low level of DNA polymorphisms. A total number of 136 polymorphic sites comprising of transitions, transversions, and insertion and deletions (InDels) were identified in the 2.9 kb sequence of Pi9 alleles. Lower variation in the form of mutations (77) (Transition + Transversion), and InDels (59) were observed in the Pi9 alleles isolated from rice landraces studied. The results showed that the Pi9 alleles of the selected rice landraces were less variable, suggesting that the rice landraces would have been exposed to less number of pathotypes across the country. The positive Tajima’s D (0.33580), P > 0.10 (not significant) was observed among the seven rice landraces, which suggests the balancing selection of Pi9 alleles. The value of synonymous substitution (-0.43337) was less than the non-synonymous substitution (0.78808). The greater non-synonymous substitution than the synonymous means that the coding region, mainly the leucine-rich repeat domain was under diversified selection. In this study, the Pi9 gene has been subjected to balancing selection with low nucleotide diversity which is different from the earlier reports, this may be because of the closeness of the rice landraces, cultivated in the same

  3. Stunt or elongate? Two opposite strategies by which rice adapts to floods.

    PubMed

    Nagai, Keisuke; Hattori, Yoko; Ashikari, Motoyuki

    2010-05-01

    Expansion of habitat is important for the perpetuation of species. In particular, plants which are sedentary must evolve specialized functions to adapt itself to new environment. Deepwater rice is cultivated mainly in the lowland areas of South and Southeast Asia that are flooded during the rainy season. The internodes of deepwater rice elongates in response to increasing water level to keep its leaves above the water surface and avoid anoxia. This elongation is stimulated by ethylene-regulated genes, Snorkel1 and Snorkel2. In contrast, when a flash flood occurs at the seedling stage, submergence-tolerant rice, which carries Submergence-1A, remains stunted and survives in water for a few weeks to avoid the energy consumption associated with plant elongation, and restarts its growth using its conserved energy after the water recedes. Interestingly, both Snorkel genes and Submergence-1A encode ethylene-responsive factor-type transcription factor and are connected to gibberellin biosynthesis or signal transduction. However, deepwater and submergence-tolerant rice seem to have opposite flooding response; namely, escape by elongation or remain stunted under water until flood recedes.

  4. Identification of drought-responsive genes in roots of upland rice (Oryza sativa L)

    PubMed Central

    Rabello, Aline R; Guimarães, Cléber M; Rangel, Paulo HN; da Silva, Felipe R; Seixas, Daniela; de Souza, Emanuel; Brasileiro, Ana CM; Spehar, Carlos R; Ferreira, Márcio E; Mehta, Ângela

    2008-01-01

    Background Rice (Oryza sativa L.) germplasm represents an extraordinary source of genes that control traits of agronomic importance such as drought tolerance. This diversity is the basis for the development of new cultivars better adapted to water restriction conditions, in particular for upland rice, which is grown under rainfall. The analyses of subtractive cDNA libraries and differential protein expression of drought tolerant and susceptible genotypes can contribute to the understanding of the genetic control of water use efficiency in rice. Results Two subtractive libraries were constructed using cDNA of drought susceptible and tolerant genotypes submitted to stress against cDNA of well-watered plants. In silico analysis revealed 463 reads, which were grouped into 282 clusters. Several genes expressed exclusively in the tolerant or susceptible genotypes were identified. Additionally, proteome analysis of roots from stressed plants was performed and 22 proteins putatively associated to drought tolerance were identified by mass spectrometry. Conclusion Several genes and proteins involved in drought-response, as well as genes with no described homologs were identified. Genes exclusively expressed in the tolerant genotype were, in general, related to maintenance of turgor and cell integrity. In contrast, in the susceptible genotype, expression of genes involved in protection against cell damage was not detected. Several protein families identified in the proteomic analysis were not detected in the cDNA analysis. There is an indication that the mechanisms of susceptibility to drought in upland rice are similar to those of lowland varieties. PMID:18922162

  5. Stable isotope ratios in irrigation water can estimate rice crop evaporation

    NASA Astrophysics Data System (ADS)

    Simpson, H. J.; Herczeg, A. L.; Meyer, W. S.

    1992-02-01

    Irrigated crops provide about one third of world food production, and the total area under irrigation has increased by more than a factor of three since 1950 [Brown, 1988]. Possibilities for further geographical expansion are limited; therefore future production increases are likely to require higher efficiency of water use. Of the major grain crops, lowland rice requires the most water, with total demand per unit area at least twice that for wheat and maize. Stable isotope abundance changes in irrigation water can provide direct indication of integrated evaporation losses exclusive of transpiration and thus provide a new tool to monitor a key parameter relevant to water use efficiency. Large enrichments of deuterium and oxygen-18 in rice field water compared to initial input water in a semi-arid region of southeastern Australia indicate high evaporation rates (7 mm day-1) during the first month following flooding. This contrasts with semi-mature rice crops which had small heavy isotope enrichments of field water, indicating low evaporation (<1 mm day-1), compared to transpiration (6 to 7 mm day-1). Over the entire rice-cropping season, evaporation accounted for about 40 per cent of total losses to the atmosphere, with transpiration providing the remainder.

  6. Genetic approaches refine ex situ lowland tapir (Tapirus terrestris) conservation.

    PubMed

    Gonçalves da Silva, Anders; Lalonde, Danielle R; Quse, Viviana; Shoemaker, Alan; Russello, Michael A

    2010-01-01

    Ex situ conservation management remains an important tool in the face of continued habitat loss and global environmental change. Here, we use microsatellite marker variation to evaluate conventional assumptions of pedigree-based ex situ population management and directly inform a captive lowland tapir breeding program within a range country. We found relatively high levels of genetic variation (N(total) = 41; mean H(E) = 0.67 across 10 variable loci) and little evidence for relatedness among founder individuals (N(founders) = 10; mean relatedness = -0.05). Seven of 29 putative parent-offspring relationships were excluded by parentage analysis based on allele sharing, and we identified 2 individuals of high genetic value to the population (mk

  7. Quaternary forest associations in lowland tropical West Africa

    NASA Astrophysics Data System (ADS)

    Miller, Charlotte S.; Gosling, William D.

    2014-01-01

    Terrestrial fossil pollen records are frequently used to reveal the response of vegetation to changes in both regional and global climate. Here we present a fossil pollen record from sediment cores extracted from Lake Bosumtwi (West Africa). This record covers the last c. 520 thousand years (ka) and represents the longest terrestrial pollen record from Africa published to date. The fossil pollen assemblages reveal dynamic vegetation change which can be broadly characterized as indicative of shifts between savannah and forest. Savannah formations are heavily dominated by grass (Poaceae) pollen (>55%) typically associated with Cyperaceae, Chenopodiaceae-Amaranthaceae and Caryophyllaceae. Forest formations are palynologically more diverse than the savannah, with the key taxa occurring in multiple forest zones being Moraceae, Celtis, Uapaca, Macaranga and Trema. The fossil pollen data indicate that over the last c. 520 ka the vegetation of lowland tropical West Africa has mainly been savannah; however six periods of forest expansion are evident which most likely correspond to global interglacial periods. A comparison of the forest assemblage composition within each interglacial suggests that the Holocene (11-0 ka) forest occurred under the wettest climate, while the forest which occurred at the time of Marine Isotope Stage 7 probably occurred under the driest climate.

  8. Soil microbial diversity patterns of a lowland spring environment.

    PubMed

    Vasileiadis, Sotirios; Puglisi, Edoardo; Arena, Maria; Cappa, Fabrizio; van Veen, Johannes A; Cocconcelli, Pier S; Trevisan, Marco

    2013-11-01

    The Po river plain lowland springs represent unique paradigms of managed environments. Their current locations used to be swamps that were drained 6-7 centuries ago, and they have been in constant use ever since. Our aims were to identify the effects of land use on the microbial communities of these soils, look for associated diversity drivers, and assess the applicability of ecology theories with respect to identified patterns. We screened the microbial diversity across a land use transect via high-throughput sequencing of partial 16S rrRNA gene amplicons. Land use had a major effect on soil properties and microbial community structures. Total organic carbon and pH were major diversity drivers for Bacteria, and pH was important for Archaea. We identified the potential contribution of soil amendments to the indigenous microbial communities, and also gained insights into potential roles of taxa in the organic carbon turnover. Verrucomicrobia coincided with the higher values of the recalcitrant organic carbon. Actinobacteria and Acidobacteria correlated with the more labile organic carbon. Finally, the higher diversity found in the soils less enzymatically active and relatively poorer in nutrients, may be explained to an extent by niche-based theories such as the resource heterogeneity hypothesis and Connell's intermediate disturbance hypothesis. © 2013 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

  9. Olfactory discrimination in the western lowland gorilla, Gorilla gorilla gorilla.

    PubMed

    Hepper, Peter G; Wells, Deborah L

    2012-04-01

    The olfactory abilities of great apes have been subject to little empirical investigation, save for a few observational reports. This study, using an habituation/dishabituation task, provides experimental evidence for a core olfactory ability, namely, olfactory discrimination, in the gorilla. In Experiment 1, six zoo-housed western lowland gorillas were individually presented with the same odour on four trials, and with a novel odour on the fifth trial. Odours (almond and vanilla) were presented on plastic balls, and behavioural responses of sniffing and chewing/licking the balls were recorded. A second experiment presented the same odour on four trials and no odour on the fifth to examine whether any dishabituation was due to the presence of a new odour or the absence of the familiar odour. Gorillas habituated their behaviour with repeated presentation of the same odour, but dishabituated, i.e. increased sniffing and chewing/licking, when presented with the novel odour. No dishabituation was noted when using water as the stimulus across all trials or when used as the novel odour. Overall, results show that gorillas are able to discriminate between odours.

  10. Groundwater Unmasked: Combining Techniques to Trace Groundwater in Lowland Streams

    NASA Astrophysics Data System (ADS)

    Kaandorp, Vince; de Hilster, Stèphanie; Doornenbal, Pieter; de Louw, Perry

    2017-04-01

    Seepage of groundwater produces a significant part of stream discharge. This base flow component is of vital important for stream functioning as it prevents streams from falling dry and provides a specific water chemistry and temperature. The interaction between groundwater and surface water is complex and highly heterogeneous both in space and time. The location of groundwater seepage can be found using several techniques which we combined to reduce uncertainties. We applied the different techniques in two lowland streams in the Netherlands, which have different geological and hydrological settings. Two glass fibre cables with a length of 1.5 km were placed in the streams for the application of Distributed Temperature Sensing (DTS). The high-frequent spatially distributed stream temperature measurements revealed local hotspots of groundwater/surface water interaction. These were compared with measurements from the groundwater tracer Radon-222, vertical flux measurements using seepage meters, vertical temperature profile measurements and visual seepage indicators. Groundwater/surface water interaction was found to vary spatially in a spectacular way: whereas seepage occurred on one side of the stream, no seepage was found on the opposite side at only meter distance. It is essential to include these small scale differences as they can result in contrasting ecological habitats. Although combining groundwater tracing methods proved to be valuable, capturing the heterogeneity and quantifying the amounts of water exchange stay the most challenging problem facing research on groundwater/surface water interaction.

  11. Quantifying the nutrient flux within a lowland karstic catchment

    NASA Astrophysics Data System (ADS)

    McCormack, T.; Naughton, O.; Johnston, P. M.; Gill, L. W.

    2015-10-01

    Nutrient contamination of surface and groundwaters is an issue of growing importance as the risks associated with agricultural runoff escalate due to increasing demands on global food production. In this study, the nutrient flux occurring within the surface and groundwaters of a lowland karst catchment in western Ireland was investigated with the aid of alkalinity sampling and a hydrological model. Water samples were tested from a variety of rivers, lakes (or turloughs), boreholes and springs at monthly intervals over three years. Alkalinity sampling was used to elucidate the contrasting hydrological functioning between different turloughs. Such disparate hydrological functioning was further investigated with the aid of a hydrological model which allowed for an estimate of allogenic and autogenic derived nutrient loading into the karst system. The model also allowed for an investigation of mixing within the turloughs, comparing observed behaviours with the hypothetical conservative behaviour allowed for by the model. Within the turloughs, nutrient concentrations were found to reduce over the flooded period, even though the turloughs hydrological functioning (and the hydrological model) suggested this should not occur. As such, it was determined that nutrient loss processes were occurring within the system. Denitrification during stable flooded periods (typically 3-4 months per year) was deemed to be the main process reducing nitrogen concentrations within the turloughs whereas phosphorus loss is thought to occur mostly via sedimentation and subsequent soil deposition. The results from this study suggest that, in stable conditions, ephemeral lakes can impart considerable nutrient losses on a karst groundwater system.

  12. Quantifying the nutrient flux within a lowland karstic catchment

    NASA Astrophysics Data System (ADS)

    McCormack, T.; Naughton, O.; Johnston, P. M.; Gill, L. W.

    2015-01-01

    Nutrient contamination of surface and groundwaters is an issue of growing importance as the risks associated with agricultural runoff escalate due to increasing demands on global food production. In this study, the nutrient flux occurring within the surface and groundwaters of a lowland karst catchment in western Ireland was investigated with the aid of alkalinity sampling and a hydrological model. Water samples were collected and tested from a variety of rivers, lakes (or turloughs), boreholes and springs at monthly intervals over a three year period. Alkalinity sampling was used to elucidate the contrasting hydrological functioning between different turloughs. Such disparate hydrological functioning was further investigated with the aid of a hydrological model which allowed for an estimate of allogenic and autogenic derived nutrient loading into the karst system. The model also allowed for an investigation of mixing within the turloughs, comparing observed behaviours with the hypothetical conservative behaviour allowed for by the model. Results indicated that at the system outlet to the sea, autogenic recharge had added approximately 35% to the total flow and approximately 85% to the total N-load. Within some turloughs, nutrient loads were found to reduce over the flooded period, even though the turloughs hydrological functioning (and the hydrological model) suggested this should not occur. As such, it was determined that nutrient loss processes were occurring within the system. Denitrification was deemed to be the main process reducing nitrogen concentrations within the turloughs whereas phosphorus loss is thought to occur mostly within the diffuse/epikarst zone.

  13. An 8700 year paleoclimate reconstruction from the southern Maya lowlands

    USGS Publications Warehouse

    Wahl, David B.; Byrne, Roger; Anderson, Lysanna

    2014-01-01

    Analysis of a sediment core from Lago Puerto Arturo, a closed basin lake in northern Peten, Guatemala, has provided an ∼8700 cal year record of climate change and human activity in the southern Maya lowlands. Stable isotope, magnetic susceptibility, and pollen analyses were used to reconstruct environmental change in the region. Results indicate a relatively wet early to middle Holocene followed by a drier late Holocene, which we interpret as reflecting long-term changes in insolation (precession). Higher frequency variability is more likely attributable to changes in ocean/atmosphere circulation in both the North Atlantic and the Pacific Oceans. Pollen and isotope data show that most of the period of prehispanic agricultural settlement, i.e. ∼5000–1000 cal yr BP, was characterized by drier conditions than previous or subsequent periods. The presence ofZea (corn) pollen through peak aridity during the Terminal Classic period (∼1250–1130 cal yr BP) suggests that drought may not have had as negative an impact as previously proposed. A dramatic negative shift in isotope values indicates an increase in precipitation after ∼950 cal yr BP (hereafter BP).

  14. Flow path and travel time dynamics in a lowland catchment.

    NASA Astrophysics Data System (ADS)

    van der Velde, Ype; de Rooij, Gerrit

    2016-04-01

    The distribution of time it takes water from the moment of precipitation to reach the catchment outlet is widely used as a characteristic for catchment flow path contributions, catchment vulnerability to pollution spreading and pollutant loads from catchments to downstream waters. However, this distribution tends to vary in time driven by variability in precipitation and evapotranspiration. Catchment scale mixing of water controls how dynamics in rainfall and evapotranspiration are translated into dynamics of travel time distributions. In this presentation we use the concept of StorAge selection (SAS) functions, that quantify catchment scale mixing of water, to describe chloride and nitrate flow. We will show how SAS functions relate to the topography and subsurface and how they are effective in describing nitrate and chloride transport. The presented analyses will combine unique datasets of high-frequency discharge and water quality concentrations with conceptual models of water flow and solute transport. Remarkable findings are the large contrasts in travel times between lowland and sloping catchments and the strong relationship between evapotranspiration and stream water nutrient concentration dynamics.

  15. Lowland gorillas and seed dispersal: the importance of nest sites.

    PubMed

    Rogers, M E; Voysey, B C; McDonald, K E; Parnell, R J; Tutin, C E

    1998-01-01

    Lowland gorillas eat the fruit and disperse the seeds of many tree species in the Lopé Reserve, Gabon. This study aimed to show whether deposition of seeds at gorilla ground nest sites conferred any advantage for germination and seedling establishment as compared to the fate of seeds deposited in gorilla dung on trails or under parents. Four tree species were chosen for study, which had a range of fruit types and fruiting patterns but which were all important foods for gorillas. Data showed that gorillas removed significant quantities of seeds from all four species and deposited them in dung at nest sites or on trail. Nest sites were not always favorable for germination, but the most favorable sites permitted the best survival and growth of any of the seedlings, including those deposited in dung on trail or scatter-dispersed under or away from parent canopies. Initial performance in the first few weeks after deposition was not always indicative of long-term survival and growth, so data collection over 1-2 years was absolutely essential. The main factors affecting seedling fate at nest sites appeared to be vegetation cover and desiccation. It is suggested that the nesting habits of gorillas are an additional factor encouraging the successful establishment of seedlings over and above the obvious advantages of large body size, gut capacity, and extended day ranges.

  16. Branchfall dominates annual carbon flux across lowland Amazonian forests

    NASA Astrophysics Data System (ADS)

    Marvin, David C.; Asner, Gregory P.

    2016-09-01

    Tropical forests play an important role in the global carbon cycle, but knowledge of interannual variation in the total tropical carbon flux and constituent carbon pools is highly uncertain. One such pool, branchfall, is an ecologically important dynamic with links to nutrient cycling, forest productivity, and drought. Identifying and quantifying branchfall over large areas would reveal the role of branchfall in carbon and nutrient cycling. Using data from repeat airborne light detection and ranging campaigns across a wide array of lowland Amazonian forest landscapes totaling nearly 100 000 ha, we find that upper canopy gaps—driven by branchfall—are pervasive features of every landscape studied, and are seven times more frequent than full tree mortality. Moreover, branchfall comprises a major carbon source on a landscape basis, exceeding that of tree mortality by 21%. On a per hectare basis, branchfall and tree mortality result in 0.65 and 0.72 Mg C ha-1 yr-1 gross source of carbon to the atmosphere, respectively. Reducing uncertainties in annual gross rates of tropical forest carbon flux, for example by incorporating large-scale branchfall dynamics, is crucial for effective policies that foster conservation and restoration of tropical forests. Additionally, large-scale branchfall mapping offers ecologists a new dimension of disturbance monitoring and potential new insights into ecosystem structure and function.

  17. Tharsis-triggered Flood Inundations of the Lowlands of Mars

    NASA Technical Reports Server (NTRS)

    Fairen, Alberto G.; Dohm, James M.; Baker, Victor R.; dePablo, Miguel A.

    2003-01-01

    Throughout the recorded history of Mars, liquid water has distinctly shaped its landscape, including the prominent circum-Chryse and the northwestern slope valleys outflow channel systems [1], and the extremely flat northern plains topography at the distal reaches of these outflow channel systems.Basing on the ideas of episodic greenhouse atmosphere and water stability on the lowlands of Mars [3], a conceptual scheme for water evolution and associated geomorphologic features on the northern plains can be proposed. This model highlights Tharsis-triggered flood inundations and their direct impact on shaping the northern plains, as well as making possible the existence of fossil and/or extant life.Possible biologic evolution throughout the resulting different climatic and hydrologic conditions would account for very distinct metabolic pathways for hypothesized organisms capable of surviving and perhaps evolving in each aqueous environment, those that existed in the dry and cold periods between the flood inundations, and those organisms that could survive both extremes. Terrestrial microbiota, chemolithotrophic and heterotrophic bacteria, provide exciting analogues for such potential extremophile existence in Mars, especially where long-lived, magmatic-driven hydrothermal activity is indicated [14].

  18. Tharsis-triggered Flood Inundations of the Lowlands of Mars

    NASA Technical Reports Server (NTRS)

    Fairen, Alberto G.; Dohm, James M.; Baker, Victor R.; dePablo, Miguel A.

    2003-01-01

    Throughout the recorded history of Mars, liquid water has distinctly shaped its landscape, including the prominent circum-Chryse and the northwestern slope valleys outflow channel systems [1], and the extremely flat northern plains topography at the distal reaches of these outflow channel systems.Basing on the ideas of episodic greenhouse atmosphere and water stability on the lowlands of Mars [3], a conceptual scheme for water evolution and associated geomorphologic features on the northern plains can be proposed. This model highlights Tharsis-triggered flood inundations and their direct impact on shaping the northern plains, as well as making possible the existence of fossil and/or extant life.Possible biologic evolution throughout the resulting different climatic and hydrologic conditions would account for very distinct metabolic pathways for hypothesized organisms capable of surviving and perhaps evolving in each aqueous environment, those that existed in the dry and cold periods between the flood inundations, and those organisms that could survive both extremes. Terrestrial microbiota, chemolithotrophic and heterotrophic bacteria, provide exciting analogues for such potential extremophile existence in Mars, especially where long-lived, magmatic-driven hydrothermal activity is indicated [14].

  19. An 8700 year paleoclimate reconstruction from the southern Maya lowlands

    NASA Astrophysics Data System (ADS)

    Wahl, David; Byrne, Roger; Anderson, Lysanna

    2014-11-01

    Analysis of a sediment core from Lago Puerto Arturo, a closed basin lake in northern Peten, Guatemala, has provided an ˜8700 cal year record of climate change and human activity in the southern Maya lowlands. Stable isotope, magnetic susceptibility, and pollen analyses were used to reconstruct environmental change in the region. Results indicate a relatively wet early to middle Holocene followed by a drier late Holocene, which we interpret as reflecting long-term changes in insolation (precession). Higher frequency variability is more likely attributable to changes in ocean/atmosphere circulation in both the North Atlantic and the Pacific Oceans. Pollen and isotope data show that most of the period of prehispanic agricultural settlement, i.e. ˜5000-1000 cal yr BP, was characterized by drier conditions than previous or subsequent periods. The presence of Zea (corn) pollen through peak aridity during the Terminal Classic period (˜1250-1130 cal yr BP) suggests that drought may not have had as negative an impact as previously proposed. A dramatic negative shift in isotope values indicates an increase in precipitation after ˜950 cal yr BP (hereafter BP).

  20. Sorption, desorption and displacement of ibuprofen, estrone, and 17β estradiol in wastewater irrigated and rainfed agricultural soils.

    PubMed

    Durán-Álvarez, Juan C; Prado, Blanca; Ferroud, Anouck; Juayerk, Narcedalia; Jiménez-Cisneros, Blanca

    2014-03-01

    Sorption and leaching potential of ibuprofen, estrone and 17β estradiol were tested in two agricultural soils: one irrigated using municipal wastewater and the other used in rainfed agriculture. Batch sorption-desorption experiments and undisturbed soil column assays were carried out using both soils to which were added a mixture of the target compounds. The three compounds were sorbed to a different extent by both soils: estrone>17β estradiol>ibuprofen. Higher sorption was observed in the irrigated soil, which was attributed to the accumulation of organic matter caused by wastewater irrigation. Desorption of hormones was hysteretic in the irrigated soil, while ibuprofen showed low hysteresis in both soils. Retardation of the compounds' displacement was consistent with the sorption pattern observed in the batch tests. Retardation factor (RF) was similar for the three compounds in the two tested soils, indicating that the target compounds are much more mobile in the soil columns than would be predicted based on their equilibrium sorption parameters. The results obtained in the experiments clarify the role of wastewater irrigated soils as a filter and degradation media for the target micropollutants.

  1. Short-term soil loss by eolian erosion in response to different rain-fed agricultural practices

    NASA Astrophysics Data System (ADS)

    Tanner, Smadar; Katra, Itzhak; Zaady, Eli

    2016-04-01

    Eolian (wind) erosion is a widespread process and a major form of soil degradation in arid and semi-arid regions. The present study examined changes in soil properties and eolian soil loss at a field scale in response to different soil treatments in two rain-fed agricultural practices. Field experiments with a boundary-layer wind tunnel and soil analysis were used to obtain the data. Two practices with different soil treatments (after harvest), mechanical tillage and stubble grazing intensities, were applied in the fallow phase of the rotation (dry season). The mechanical tillage and the stubble grazing had an immediate and direct effects on soil aggregation but not on the soil texture, and the contents of soil water, organic matter, and CaCO3. Higher erosion rates, that was measured as fluxes of total eolian sediment and particulate matter <10 μm (PM10), were recorded under mechanical tillage and grazing intensities compared with the undisturbed topsoil of the control plots. The erosion rates were higher in grazing plots than in tillage plots. The calculated soil fluxes in this study indicate potentially rapid soil degradation due to loss of fine particles by wind. The finding may have implications for long-term management of agricultural soils in semi-arid areas.

  2. [Effects of limited supplemental irrigation with catchment rainfall on potato growth in rainfed areas of western Loess Plateau].

    PubMed

    Qin, Shu-Hao; Zhang, Jun-Lian; Wang, Di; Pu, Yu-Lin

    2009-11-01

    Field experiments were conducted to study the effects of limited supplemental irrigation with catchment rainfall on the growth of potato cultivars Daxiyang and Tongshu 23 in rainfed areas of western Loess Plateau. Supplemental irrigation with catchment rainfall at seedling stage increased the potato yield significantly, and the increment was higher for Daxiyang than for Tongshu No. 23. Supplemental irrigation at tuber expanding stage increased the yield of Tongshu 23, but decreased the yield of Daxiyang. Low amount of supplemental irrigation (45 mm) increased the water use efficiency (WUE) and irrigation water use efficiency (IWUE) of Tongshu 23. For Daxiyang, its WUE and IWUE were higher when the supplemental irrigation was made at seedling stage than at tuber expanding stage. Supplemental irrigation increased the tuber yield and the percentages of bigger and medium tubers of Tongshu 23, but the percentages of green and blet tubers were also increased. As for Daxiyang, supplemental irrigation increased the percentages of bigger and smaller tubers, as well as the percentage of blet tuber.

  3. A Fuzzy Rule Based Decision Support System for Identifying Location of Water Harvesting Technologies in Rainfed Agricultural Regions

    NASA Astrophysics Data System (ADS)

    Chaubey, I.; Vema, V. K.; Sudheer, K.

    2016-12-01

    Site suitability evaluation of water conservation structures in water scarce rainfed agricultural areas consist of assessment of various landscape characteristics and various criterion. Many of these landscape characteristic attributes are conveyed through linguistic terms rather than precise numeric values. Fuzzy rule based system are capable of incorporating uncertainty and vagueness, when various decision making criteria expressed in linguistic terms are expressed as fuzzy rules. In this study a fuzzy rule based decision support system is developed, for optimal site selection of water harvesting technologies. Water conservation technologies like farm ponds, Check dams, Rock filled dams and percolation ponds aid in conserving water for irrigation and recharging aquifers and development of such a system will aid in improving the efficiency of the structures. Attributes and criteria involved in decision making are classified into different groups to estimate the suitability of the particular technology. The developed model is applied and tested on an Indian watershed. The input attributes are prepared in raster format in ArcGIS software and suitability of each raster cell is calculated and output is generated in the form of a thematic map showing the suitability of the cells pertaining to different technologies. The output of the developed model is compared against the already existing structures and results are satisfactory. This developed model will aid in improving the sustainability and efficiency of the watershed management programs aimed at enhancing in situ moisture content.

  4. [Variation analysis on the grain yield and main agronomic traits of spring wheat in rainfed regions of China].

    PubMed

    Chang, Lei; Chai, Shou-xi; Yang, De-long; Lu, Qing-lin

    2010-11-01

    Based on the grain yield data of spring wheat from the 2002-2005 regional trials with 13 cultivars (lines) on the rainfed farmlands at 18 locations of China, and by using variance analysis and GGE (genotype main effect plus genotype-by-environment interaction) biplot, this paper studied the effects of genotype, environment, and genotype x environment interaction (GEI) on the yield variation of spring wheat and the yield stability of different cultivars (lines). Comparing with genotype and GEI, the environment had much more contribution on the yield variation, accounting for 87.5%-92.0% of the total. In the GEI items, genotype x location had the greatest effect, whereas genotype x year had the smallest one. The average yield of modern spring wheat genotypes across years and locations in China was 2550 kg x hm(-2). Among the three yield components, thousand kernel weight (TKW) had the least variation under environmental change. The main environment factors affecting the yield variation were annual accumulated temperature ( > or =10 degrees C), precipitation in growth season, mean air temperature, altitude, annual precipitation, and frost-free period. The grain yield had significant positive correlations with spike number per unit area (SPU) (r = 0.675**), TKW (r = 0.456**), and kernels per spike (KPS) (r = 0.581**), and the SPU, KPS and TKW also had positive correlations (r = 0.244-0.480**) with each other, implying that these three yield components might be increased or improved synchronously.

  5. Soil-dissipation kinetics of twelve herbicides used on a rain-fed barley crop in Spain.

    PubMed

    Díez, Cristina; Barrado, Enrique

    2010-06-01

    This study evaluated the dissipation kinetics under actual field conditions of twelve herbicides in a typical xerofluvent soil in Castilla y León (north central Spain) sustaining barley. The type of soil selected was that typically used in the Castilla y León region to cultivate barley under a rain-fed alternating crop-fallow rotation regimen. Treatments were conducted in spring as two replicates and the soil was sampled every day during the first week, once a week for the following few weeks and thereafter once every month. Soil samples were extracted with a suitable mixture of acetone, water and acetic acid (30:7.5:0.3) before their analysis by GC-MS (gas chromatography-mass spectrometry). Dissipation of the herbicides was well described by a biphasic kinetics pattern. The dissipation times DT50 and DT90 were in general lower than those reported in the literature, owing to a high initial dissipation rate because of volatilization and photolysis processes caused by high environmental temperatures. Herbicide degradation was also enhanced by their lack of sorption by this low colloid-content soil. However, the most persistent herbicides, triallate, flamprop, pendimethalin, terbutryn, and isoproturon, remained for 286 to 372 days in the soil, because low water and organic carbon content impaired microbial growth. In contrast, the phenoxy acid herbicides dissipated rapidly, with no detectable residues detected on harvesting the crop.

  6. The submergence tolerance regulator SUB1A mediates crosstalk between submergence and drought tolerance in rice.

    PubMed

    Fukao, Takeshi; Yeung, Elaine; Bailey-Serres, Julia

    2011-01-01

    Submergence and drought are major constraints to rice (Oryza sativa) production in rain-fed farmlands, both of which can occur sequentially during a single crop cycle. SUB1A, an ERF transcription factor found in limited rice accessions, dampens ethylene production and gibberellic acid responsiveness during submergence, economizing carbohydrate reserves and significantly prolonging endurance. Here, we evaluated the functional role of SUB1A in acclimation to dehydration. Comparative analysis of genotypes with and without SUB1A revealed that SUB1A enhanced recovery from drought at the vegetative stage through reduction of leaf water loss and lipid peroxidation and increased expression of genes associated with acclimation to dehydration. Overexpression of SUB1A augmented ABA responsiveness, thereby activating stress-inducible gene expression. Paradoxically, vegetative tissue undergoes dehydration upon desubmergence even though the soil contains sufficient water, indicating that leaf desiccation occurs in the natural progression of a flooding event. Desubmergence caused the upregulation of gene transcripts associated with acclimation to dehydration, with higher induction in SUB1A genotypes. SUB1A also restrained accumulation of reactive oxygen species (ROS) in aerial tissue during drought and desubmergence. Consistently, SUB1A increased the abundance of transcripts encoding ROS scavenging enzymes, resulting in enhanced tolerance to oxidative stress. Therefore, in addition to providing robust submergence tolerance, SUB1A improves survival of rapid dehydration following desubmergence and water deficit during drought.

  7. Rice disease management under organic production

    USDA-ARS?s Scientific Manuscript database

    Interest in organic rice production has increased because of the increased market demand for organic rice. Texas organic rice acreage has constantly increased over the last decade, reaching 32,000 acres in 2012. Texas is now the leading state in organic rice production in the U.S. Organic rice is p...

  8. Organic Rice Production: Challenges and Opportunities

    USDA-ARS?s Scientific Manuscript database

    The market demand for organically produced rice has grown steadily with the majority of the acreage now being located in Texas and California. A wide range of organic products are marketed including conventional long and medium grain rice, aromatic or scented rice, rice with colored bran, and rice f...

  9. Do NERICA rice cultivars express resistance to Striga hermonthica (Del.) Benth. and Striga asiatica (L.) Kuntze under field conditions?

    PubMed

    Rodenburg, Jonne; Cissoko, Mamadou; Kayeke, Juma; Dieng, Ibnou; Khan, Zeyaur R; Midega, Charles A O; Onyuka, Enos A; Scholes, Julie D

    2015-01-01

    The parasitic weeds Striga asiatica and Striga hermonthica cause high yield losses in rain-fed upland rice in Africa. Two resistance classes (pre- and post-attachment) and several resistant genotypes have been identified among NERICA (New Rice for Africa) cultivars under laboratory conditions (in vitro) previously. However, little is known about expression of this resistance under field conditions. Here we investigated (1) whether resistance exhibited under controlled conditions would express under representative Striga-infested field conditions, and (2) whether NERICA cultivars would achieve relatively good grain yields under Striga-infested conditions. Twenty-five rice cultivars, including all 18 upland NERICA cultivars, were screened in S. asiatica-infested (in Tanzania) and S. hermonthica-infested (in Kenya) fields during two seasons. Additionally, a selection of cultivars was tested in vitro, in mini-rhizotron systems. For the first time, resistance observed under controlled conditions was confirmed in the field for NERICA-2, -5, -10 and -17 (against S. asiatica) and NERICA-1 to -5, -10, -12, -13 and -17 (against S. hermonthica). Despite high Striga-infestation levels, yields of around 1.8 t ha(-1) were obtained with NERICA-1, -9 and -10 (in the S. asiatica-infested field) and around 1.4 t ha(-1) with NERICA-3, -4, -8, -12 and -13 (in the S. hermonthica-infested field). In addition, potential levels of tolerance were identified in vitro, in NERICA-1, -17 and -9 (S. asiatica) and in NERICA-1, -17 and -10 (S. hermonthica). These findings are highly relevant to rice agronomists and breeders and molecular geneticists working on Striga resistance. In addition, cultivars combining broad-spectrum resistance with good grain yields in Striga-infested fields can be recommended to rice farmers in Striga-prone areas.

  10. Branching in rice.

    PubMed

    Wang, Yonghong; Li, Jiayang

    2011-02-01

    Rice branching, including the formation of tillers and panicle branches, has been well investigated over the past several years because of its agronomic importance. A major breakthrough in elucidating rice tillering in the recent years was the discovery of strigolactones, a specific group of terpenoid lactones that can inhibit axillary bud outgrowth. Since that discovery, new tillering mutants, that is, dwarf 27 (d27) or dwarf14 (d14, also reported as d88 or htd2), have been identified with reduced strigolactone levels or strigolactone response. DWARF27 (D27) and DWARF14 (D14) probably act on strigolactone biosynthesis and signal transduction, respectively. Additionally, several genes controlling panicle branches have been identified recently. DEP1 and IPA1/WFP are essential dominant/semidominant regulators that determine rice panicle branches and thus affect the grain yields. More importantly, dep1 and ipa1 alleles have been shown to be applicable for the improvement of rice grain yields in molecular breeding. Copyright © 2010 Elsevier Ltd. All rights reserved.

  11. Rice: chemistry and technology.

    USDA-ARS?s Scientific Manuscript database

    Rice has taken center stage this last decade, not only as an important provider of nourishment for the world’s population, but as a grain now recognized as having many unique nutritional and functional attributes with potential to be captured in a multitude of value-added food and non-food applicati...

  12. Exploring Japan through Rice.

    ERIC Educational Resources Information Center

    Wojtan, Linda S.

    1998-01-01

    Explores the role of rice in Japanese culture by presenting historical background and teaching activities in a variety of categories, such as language, sociology, history, and contemporary politics. Suggests teachers create cross-cultural comparisons; for example, the role of corn in the United States. Provides a list of teacher resources. (CMK)

  13. Rice bran phytonutrients

    USDA-ARS?s Scientific Manuscript database

    The bran layer of the whole grain rice contains potential health-beneficial compounds. These include vitamin E homologs (tocopherols, tocotrienols), oryzanol fractions, simple phenolics and poly-phenolics. These are antioxidants that are believed to provide protection against diseases such as cancer...

  14. Hyperspectral Analysis of Rice Phenological Stages in Northeast China

    NASA Astrophysics Data System (ADS)

    Gnyp, M. L.; Yao, Y.; Yu, K.; Huang, S.; Aasen, H.; Lenz-Wiedemann, V. I. S.; Miao, Y.; Bareth, G.

    2012-07-01

    The objective of this contribution is to monitor rice (Oryza sativa L., irrigated lowland rice) growth with multitemporal hyperspectral data during different phenological stages in Northeast China (Sanjiang Plain). Multitemporal hyperspectral data were measured with field spectroradiometers (ASD Inc.: QualitySpec and FieldSpec3) for two field experiments and nine farmers' fields. The field measurements were carried out together with corresponding measurements of agronomic data (aboveground biomass [AGB], Leaf Area Index [LAI], number of tillers). Eight selected standard hyperspectral vegetation indices (VIs), proved in several studies to be highly correlated with AGB or LAI, were calculated on the measured experimental field data. Additionally, the best two-band combinations for the Normalized Ratio Index (NRI) were determined. The results indicate that the NRI performed better than the selected standard VIs at the stages of stem elongation, booting and heading and also across all stages. Especially during the stem elongation stage (R2 = 0.76) and across all stages (R2 = 0.70), the NRI performed best. When applying the NRI on the farmers' field data, the performance was lower (R2 < 0.60). Overall, the sensitive individual wavelengths (±10 nm) for the best two-band combinations were detected at 711 and 799 nm (for tillering stage), 1575 and 1678 nm (for stem elongation stage), 515 and 695 nm (for booting stage), and 533 and 713 nm (for all stages). The results suggest that hyperspectral-based methods can estimate paddy rice AGB with a satisfying accuracy. In the context of precision agriculture, the findings are useful for future development of new hyperspectral devices such as scanners or cameras which could be fixed on tractors or unmanned aerial vehicles (UAVs).

  15. 7 CFR 868.310 - Grades and grade requirements for the classes Long Grain Milled Rice, Medium Grain Milled Rice...

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... Grain Milled Rice, Medium Grain Milled Rice, Short Grain Milled Rice, and Mixed Milled Rice. (See also Â... classes Long Grain Milled Rice, Medium Grain Milled Rice, Short Grain Milled Rice, and Mixed Milled Rice..., but any device or method which gives equivalent results may be used. 4 These limits do not apply to...

  16. 7 CFR 868.310 - Grades and grade requirements for the classes Long Grain Milled Rice, Medium Grain Milled Rice...

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... Grain Milled Rice, Medium Grain Milled Rice, Short Grain Milled Rice, and Mixed Milled Rice. (See also Â... classes Long Grain Milled Rice, Medium Grain Milled Rice, Short Grain Milled Rice, and Mixed Milled Rice..., but any device or method which gives equivalent results may be used. 4 These limits do not apply to...

  17. Assessing Weather-Yield Relationships in Rice at Local Scale Using Data Mining Approaches

    PubMed Central

    Delerce, Sylvain; Dorado, Hugo; Grillon, Alexandre; Rebolledo, Maria Camila; Prager, Steven D.; Patiño, Victor Hugo; Garcés Varón, Gabriel; Jiménez, Daniel

    2016-01-01

    Seasonal and inter-annual climate variability have become important issues for farmers, and climate change has been shown to increase them. Simultaneously farmers and agricultural organizations are increasingly collecting observational data about in situ crop performance. Agriculture thus needs new tools to cope with changing environmental conditions and to take advantage of these data. Data mining techniques make it possible to extract embedded knowledge associated with farmer experiences from these large observational datasets in order to identify best practices for adapting to climate variability. We introduce new approaches through a case study on irrigated and rainfed rice in Colombia. Preexisting observational datasets of commercial harvest records were combined with in situ daily weather series. Using Conditional Inference Forest and clustering techniques, we assessed the relationships between climatic factors and crop yield variability at the local scale for specific cultivars and growth stages. The analysis showed clear relationships in the various location-cultivar combinations, with climatic factors explaining 6 to 46% of spatiotemporal variability in yield, and with crop responses to weather being non-linear and cultivar-specific. Climatic factors affected cultivars differently during each stage of development. For instance, one cultivar was affected by high nighttime temperatures in the reproductive stage but responded positively to accumulated solar radiation during the ripening stage. Another was affected by high nighttime temperatures during both the vegetative and reproductive stages. Clustering of the weather patterns corresponding to individual cropping events revealed different groups of weather patterns for irrigated and rainfed systems with contrasting yield levels. Best-suited cultivars were identified for some weather patterns, making weather-site-specific recommendations possible. This study illustrates the potential of data mining for

  18. Assessing Weather-Yield Relationships in Rice at Local Scale Using Data Mining Approaches.

    PubMed

    Delerce, Sylvain; Dorado, Hugo; Grillon, Alexandre; Rebolledo, Maria Camila; Prager, Steven D; Patiño, Victor Hugo; Garcés Varón, Gabriel; Jiménez, Daniel

    2016-01-01

    Seasonal and inter-annual climate variability have become important issues for farmers, and climate change has been shown to increase them. Simultaneously farmers and agricultural organizations are increasingly collecting observational data about in situ crop performance. Agriculture thus needs new tools to cope with changing environmental conditions and to take advantage of these data. Data mining techniques make it possible to extract embedded knowledge associated with farmer experiences from these large observational datasets in order to identify best practices for adapting to climate variability. We introduce new approaches through a case study on irrigated and rainfed rice in Colombia. Preexisting observational datasets of commercial harvest records were combined with in situ daily weather series. Using Conditional Inference Forest and clustering techniques, we assessed the relationships between climatic factors and crop yield variability at the local scale for specific cultivars and growth stages. The analysis showed clear relationships in the various location-cultivar combinations, with climatic factors explaining 6 to 46% of spatiotemporal variability in yield, and with crop responses to weather being non-linear and cultivar-specific. Climatic factors affected cultivars differently during each stage of development. For instance, one cultivar was affected by high nighttime temperatures in the reproductive stage but responded positively to accumulated solar radiation during the ripening stage. Another was affected by high nighttime temperatures during both the vegetative and reproductive stages. Clustering of the weather patterns corresponding to individual cropping events revealed different groups of weather patterns for irrigated and rainfed systems with contrasting yield levels. Best-suited cultivars were identified for some weather patterns, making weather-site-specific recommendations possible. This study illustrates the potential of data mining for

  19. Rice Glycosyltransferase (GT) Phylogenomic Database

    DOE Data Explorer

    Ronald, Pamela

    The Ronald Laboratory staff at the University of California-Davis has a primary research focus on the genes of the rice plant. They study the role that genetics plays in the way rice plants respond to their environment. They created the Rice GT Database in order to integrate functional genomic information for putative rice Glycosyltransferases (GTs). This database contains information on nearly 800 putative rice GTs (gene models) identified by sequence similarity searches based on the Carbohydrate Active enZymes (CAZy) database. The Rice GT Database provides a platform to display user-selected functional genomic data on a phylogenetic tree. This includes sequence information, mutant line information, expression data, etc. An interactive chromosomal map shows the position of all rice GTs, and links to rice annotation databases are included. The format is intended to "facilitate the comparison of closely related GTs within different families, as well as perform global comparisons between sets of related families." [From http://ricephylogenomics.ucdavis.edu/cellwalls/gt/genInfo.shtml] See also the primary paper discussing this work: Peijian Cao, Laura E. Bartley, Ki-Hong Jung and Pamela C. Ronalda. Construction of a Rice Glycosyltransferase Phylogenomic Database and Identification of Rice-Diverged Glycosyltransferases. Molecular Plant, 2008, 1(5): 858-877.

  20. An 85-ka Paleoclimate Record From Lowland Central America

    NASA Astrophysics Data System (ADS)

    Escobar, J.; Hodell, D. A.; Anselmetti, F. S.; Ariztegui, D.; Brenner, M.; Curtis, J. H.; Gilli, A.; Grzesik, D. A.; Guilderson, T. J.; Müller, A. D.; Bush, M. B.; Correa-Metrio, A.; Kutterolf, S.

    2008-05-01

    Lake sediment cores recovered at seven sites in Lake Peten Itza, northern Guatemala, contain a record of climate change from lowland Central America extending back to ~200 ka. Drill cores at site PI-6 contain a high- resolution record (1 m/ka) for the last ~85 ka. Peten climate generally varied between wetter conditions during interstadials and a drier state during stadials of Marine Isotope Stage (MIS) 3. The most arid periods coincided with Heinrich Events in the North Atlantic and reductions in the strength of meridional overturning circulation. The pattern of clay-gypsum (wet-dry) oscillations during MIS 3 closely resembles the temperature record from Greenland ice cores and North Atlantic marine sediment cores and precipitation proxies from the Cariaco Basin. Previous studies suggested that cool, dry conditions prevailed in the region during the last glacial maximum (LGM) chronozone, ~23 to 18 ka BP. Sedimentologic and palynologic data support a moist climate in the Peten lowlands during this period whenvegetation consisted of a temperate pine-oak forest. This finding contradicts the previous inferences. At the end of the LGM, Peten climate switched abruptly from moist to arid conditions during the so-called "Mystery Period" from 18 to 14.9 ka. Moister conditions prevailed during the warmer Bolling-Allerod (14.7 to 12.8 ka), with the exception of a drier climate, with greater δ18O values between ca. 14.5 and 13.5 ka BP. This drier period in Central America coincided with Meltwater Pulse 1A (14.1- 13.5 ka) (Fairbanks et al., 2005) when a substantial volume of glacial meltwater was introduced to the Gulf of Mexico (e.g. Flower et al., 2004). The greatest δ18O values in Peten Itza occurred at 13.7 ka coinciding with the greatest rate of sea level rise (4.3 cm yr-1) at 13.9 ka. In contrast, sea surface temperature (SST) reconstructions (Lea et al., 2003), color reflectance, and elemental (Fe, Ti) data (Peterson et al., 2000) from Cariaco Basin cores, north of

  1. QTL Mapping in Three Rice Populations Uncovers Major Genomic Regions Associated with African Rice Gall Midge Resistance.

    PubMed

    Yao, Nasser; Lee, Cheng-Ruei; Semagn, Kassa; Sow, Mounirou; Nwilene, Francis; Kolade, Olufisayo; Bocco, Roland; Oyetunji, Olumoye; Mitchell-Olds, Thomas; Ndjiondjop, Marie-Noëlle

    2016-01-01

    African rice gall midge (AfRGM) is one of the most destructive pests of irrigated and lowland African ecologies. This study aimed to identify the quantitative trait loci (QTL) associated with AfRGM pest incidence and resistance in three independent bi-parental rice populations (ITA306xBW348-1, ITA306xTOG7106 and ITA306xTOS14519), and to conduct meta QTL (mQTL) analysis to explore whether any genomic regions are conserved across different genetic backgrounds. Composite interval mapping (CIM) conducted on the three populations independently uncovered a total of 28 QTLs associated with pest incidence (12) and pest severity (16). The number of QTLs per population associated with AfRGM resistance varied from three in the ITA306xBW348-1 population to eight in the ITA306xTOG7106 population. Each QTL individually explained 1.3 to 34.1% of the phenotypic variance. The major genomic region for AfRGM resistance had a LOD score and R2 of 60.0 and 34.1% respectively, and mapped at 111 cM on chromosome 4 (qAfrGM4) in the ITA306xTOS14519 population. The meta-analysis reduced the number of QTLs from 28 to 17 mQTLs, each explaining 1.3 to 24.5% of phenotypic variance, and narrowed the confidence intervals by 2.2 cM. There was only one minor effect mQTL on chromosome 1 that was common in the TOS14519 and TOG7106 genetic backgrounds; all other mQTLs were background specific. We are currently fine-mapping and validating the major effect genomic region on chromosome 4 (qAfRGM4). This is the first report in mapping the genomic regions associated with the AfRGM resistance, and will be highly useful for rice breeders.

  2. Satellite Perspectives on Highland - Lowland Human Interaction in Ancient Syria

    NASA Astrophysics Data System (ADS)

    Lönnqvist, M.; Törmä, M.; Lönnqvist, K.; Nuñez, M.

    2012-08-01

    Nowadays we can travel by GoogleEarth 3D to Syria (http://www.worldcountries.info/GoogleEarth/GoogleEarth-Syria.php) and zoom in on the desert landscape of the mountainous region of Jebel Bishri between the Euphrates river and the Syrian Desert. This is the area, where the Finnish archaeological survey and mapping project SYGIS worked in 2000-2010 studying the relationship of humans with their environment from ancient times to the present. What kind of landscape views and visions did the ancients have and how did they utilize them? The present paper focuses on seeking answers for these questions by combining satellite data sources, such as imagery and radar data, with location information of archaeological remains collected on the ground. Landsat as well as QuickBird imagery have been fused with SRTM mission and ASTER DEM data in creating 3D landscape models and fly-over simulations. The oasis of El Kowm on the western piedmont of the mountain seems to have served as a base camp for early huntergatherers and pastoral nomads dwelling seasonally in the region of Jebel Bishri. According to the archaeological finds, the interaction between the lowland and the mountain people already started during the Palaeolithic era but was continued by pastoral nomads of the region from the Neolithic period onwards. The Upper Palaeolithic period meant a clear change in cognitive thinking and obviously in understanding the properties of landscape, visibility and perceiving sceneries in 3D. Mobility of hunter-gatherers and pastoral nomads is based on subsistence economy, but mobility also enhances visions and prospects of phenomena appearing in the horizon.

  3. Excess growing-season water limits lowland black spruce productivity

    NASA Astrophysics Data System (ADS)

    Dymond, S.; Kolka, R. K.; Bolstad, P. V.; Gill, K.; Curzon, M.; D'Amato, A. W.

    2015-12-01

    The annual growth of many tree species is limited by water availability, with growth increasing as water becomes less scarce. In lowland bogs of northern Minnesota, however, black spruce (Picea mariana) is often exposed to excess water via high water table elevations. These trees grow in thick deposits of organic mucky peat and often have shallow rooting systems to avoid the complete submersion of roots in water. While it is generally believed that black spruce decrease growth rates with rising water table elevations, this hypothesis has not been tested in situ. We used a unique, 50-year record of daily bog water table elevations at the Marcell Experimental Forest (MEF) in northern Minnesota to investigate the relationship between climate and black spruce productivity. Nine 1/20th ha circular plots were established in five different bogs and tree height, diameter-at-breast-height (DBH), and crown class were recorded. Additionally, two perpendicular cores were collected on all trees greater than 10 cm diameter-at-breast-height. Tree cores were sanded, mounted, cross-dated, and de-trended according to standard dendrochronological procedures. Ring width measurements were correlated with precipitation, temperature, and water table elevation using package BootRes in R to determine the climatic variables most associated with stand level productivity. Across the different plots, we found that early growing season water table elevation (May and June) was negatively correlated with both individual and stand-level black spruce growth (p < 0.01), while growth was positively correlated with March temperatures (p < 0.01). No significant relationships existed between black spruce growth and monthly precipitation. If summer water table elevations in these peatland ecosystems rise as is anticipated with more extreme precipitation events due to climate change, we could see an overall decrease in the stand level productivity of black spruce.

  4. Site response and attenuation in the Puget Lowland, Washington State

    USGS Publications Warehouse

    Pratt, T.L.; Brocher, T.M.

    2006-01-01

    Simple spectral ratio (SSR) and horizontal-to-vertical (HN) site-response estimates at 47 sites in the Puget Lowland of Washington State document significant attenuation of 1.5- to 20-Hz shear waves within sedimentary basins there. Amplitudes of the horizontal components of shear-wave arrivals from three local earthquakes were used to compute SSRs with respect to the average of two bedrock sites and H/V spectral ratios with respect to the vertical component of the shear-wave arrivals at each site. SSR site-response curves at thick basin sites show peak amplifications of 2 to 6 at frequencies of 3 to 6 Hz, and decreasing spectra amplification with increasing frequency above 6 Hz. SSRs at nonbasin sites show a variety of shapes and larger resonance peaks. We attribute the spectral decay at frequencies above the amplification peak at basin sites to attenuation within the basin strata. Computing the frequency-independent, depth-dependent attenuation factor (Qs,int) from the SSR spectral decay between 2 and 20 Hz gives values of 5 to 40 for shallow sedimentary deposits and about 250 for the deepest sedimentary strata (7 km depth). H/V site responses show less spectral decay than the SSR responses but contain many of the same resonance peaks. We hypothesize that the H/V method yields a flatter response across the frequency spectrum than SSRs because the H/V reference signal (vertical component of the shear-wave arrivals) has undergone a degree of attenuation similar to the horizontal component recordings. Correcting the SSR site responses for attenuation within the basins by removing the spectral decay improves agreement between SSR and H/V estimates.

  5. Echocardiographic parameters of captive western lowland gorillas (Gorilla gorilla gorilla).

    PubMed

    Murphy, Hayley Weston; Dennis, Patricia; Devlin, William; Meehan, Tom; Kutinsky, Ilana

    2011-12-01

    A total of 163 echocardiographic studies on western lowland gorillas (Gorilla gorilla gorilla) were submitted for evaluation; 140 from 99 animals were suitable for analysis. Of these, 81 studies (42 studies from 35 males ranging in age from 11-41+ yr and 39 studies from 31 females ranging in age from 11-41+ yr) are reported here. Three studies from 3 females and 56 studies from 30 males were excluded from this report due to cardiac abnormalities. Cardiac parameters measured were aortic root (Ao Rt) diameter and left atrial (L atrium) size. Left ventricular (LV) measurements included left ventricular internal diameter in systole (LVID(s)) and diastole (LVID(d)) as well as diastolic septal (IVS) and posterior wall thickness (LVPW). Values considered to be normal in females > 11 yr of age were: Ao Rt < 3.5 cm, L atrium < 4.0 cm, LVID(d) < 5.0 cm, IVS < 1.4 cm, LVPW < 1.4 cm, and ejection fraction (EF) > 60%. The data from male gorillas show a separation in animals based on three cardiac parameters: systolic function, LV cavity size, and LV wall thickness. Male gorillas > 11 yr of age fall into two groups; unaffected and affected. Unaffected animals are defined as those with no echocardiographic abnormalities and a consistent Ao Rt of < 4.0 cm, LVID(d) of < 6.0 cm, IVS and LVPW of <1.5 cm, and an EF of > 58%. The affected group consisted of male gorillas that exhibited changes in echocardiographic parameters representing the presence of cardiovascular disease. The results determined in this database, gathered from data collected from 1999-2009, suggest a sex-based difference between males and females with predominantly males demonstrating evidence of cardiac disease. The most striking finding seen in this study is that of progressive LV hypertrophy and depressed LV EF in affected adult male gorillas.

  6. Wild Western Lowland Gorillas Signal Selectively Using Odor

    PubMed Central

    Klailova, Michelle; Lee, Phyllis C.

    2014-01-01

    Mammals communicate socially through visual, auditory and chemical signals. The chemical sense is the oldest sense and is shared by all organisms including bacteria. Despite mounting evidence for social chemo-signaling in humans, the extent to which it modulates behavior is debated and can benefit from comparative models of closely related hominoids. The use of odor cues in wild ape social communication has been only rarely explored. Apart from one study on wild chimpanzee sniffing, our understanding is limited to anecdotes. We present the first study of wild gorilla chemo-communication and the first analysis of olfactory signaling in relation to arousal levels and odor strength in wild apes. If gorilla scent is used as a signaling mechanism instead of only a sign of arousal or stress, odor emission should be context specific and capable of variation as a function of the relationships between the emitter and perceiver(s). Measured through a human pungency scale, we determined the factors that predicted extreme levels of silverback odor for one wild western lowland gorilla (Gorilla gorilla gorilla) group silverback. Extreme silverback odor was predicted by the presence and intensity of inter-unit interactions, silverback anger, distress and long-calling auditory rates, and the absence of close proximity between the silverback and mother of the youngest infant. Odor strength also varied according to the focal silverback's strategic responses during high intensity inter-unit interactions. Silverbacks appear to use odor as a modifiable form of communication; where odor acts as a highly flexible, context dependent signaling mechanism to group members and extra-group units. The importance of olfaction to ape social communication may be especially pertinent in Central African forests where limited visibility may necessitate increased reliance on other senses. PMID:25006973

  7. Wild western lowland gorillas signal selectively using odor.

    PubMed

    Klailova, Michelle; Lee, Phyllis C

    2014-01-01

    Mammals communicate socially through visual, auditory and chemical signals. The chemical sense is the oldest sense and is shared by all organisms including bacteria. Despite mounting evidence for social chemo-signaling in humans, the extent to which it modulates behavior is debated and can benefit from comparative models of closely related hominoids. The use of odor cues in wild ape social communication has been only rarely explored. Apart from one study on wild chimpanzee sniffing, our understanding is limited to anecdotes. We present the first study of wild gorilla chemo-communication and the first analysis of olfactory signaling in relation to arousal levels and odor strength in wild apes. If gorilla scent is used as a signaling mechanism instead of only a sign of arousal or stress, odor emission should be context specific and capable of variation as a function of the relationships between the emitter and perceiver(s). Measured through a human pungency scale, we determined the factors that predicted extreme levels of silverback odor for one wild western lowland gorilla (Gorilla gorilla gorilla) group silverback. Extreme silverback odor was predicted by the presence and intensity of inter-unit interactions, silverback anger, distress and long-calling auditory rates, and the absence of close proximity between the silverback and mother of the youngest infant. Odor strength also varied according to the focal silverback's strategic responses during high intensity inter-unit interactions. Silverbacks appear to use odor as a modifiable form of communication; where odor acts as a highly flexible, context dependent signaling mechanism to group members and extra-group units. The importance of olfaction to ape social communication may be especially pertinent in Central African forests where limited visibility may necessitate increased reliance on other senses.

  8. Specific Vicariance of Two Primeval Lowland Forest Lichen Indicators

    NASA Astrophysics Data System (ADS)

    Kubiak, Dariusz; Osyczka, Piotr

    2017-06-01

    To date, the lichens Chrysothrix candelaris and Varicellaria hemisphaerica have been classified as accurate primeval lowland forest indicators. Both inhabit particularly valuable remnants of oak-hornbeam forests in Europe, but tend toward a specific kind of vicariance on a local scale. The present study was undertaken to determine habitat factors responsible for this phenomenon and verify the indicative and conservation value of these lichens. The main spatial and climatic parameters that, along with forest structure, potentially affect their distribution patterns and abundance were analysed in four complexes with typical oak-hornbeam stands in NE Poland. Fifty plots of 400 m2 each were chosen for detailed examination of stand structure and epiphytic lichens directly associated with the indicators. The study showed that the localities of the two species barely overlap within the same forest community in a relatively small geographical area. The occurrence of Chrysothrix candelaris depends basically only on microhabitat space provided by old oaks and its role as an indicator of the ecological continuity of habitat is limited. Varicellaria hemisphaerica is not tree specific but a sufficiently high moisture of habitat is essential for the species and it requires forests with high proportion of deciduous trees in a wide landscape scale. Local landscape-level habitat continuity is more important for this species than the current age of forest stand. Regardless of the indicative value, localities of both lichens within oak-hornbeam forests deserve the special protection status since they form unique assemblages of exclusive epiphytes, including those with high conservation value.

  9. Specific Vicariance of Two Primeval Lowland Forest Lichen Indicators.

    PubMed

    Kubiak, Dariusz; Osyczka, Piotr

    2017-06-01

    To date, the lichens Chrysothrix candelaris and Varicellaria hemisphaerica have been classified as accurate primeval lowland forest indicators. Both inhabit particularly valuable remnants of oak-hornbeam forests in Europe, but tend toward a specific kind of vicariance on a local scale. The present study was undertaken to determine habitat factors responsible for this phenomenon and verify the indicative and conservation value of these lichens. The main spatial and climatic parameters that, along with forest structure, potentially affect their distribution patterns and abundance were analysed in four complexes with typical oak-hornbeam stands in NE Poland. Fifty plots of 400 m(2) each were chosen for detailed examination of stand structure and epiphytic lichens directly associated with the indicators. The study showed that the localities of the two species barely overlap within the same forest community in a relatively small geographical area. The occurrence of Chrysothrix candelaris depends basically only on microhabitat space provided by old oaks and its role as an indicator of the ecological continuity of habitat is limited. Varicellaria hemisphaerica is not tree specific but a sufficiently high moisture of habitat is essential for the species and it requires forests with high proportion of deciduous trees in a wide landscape scale. Local landscape-level habitat continuity is more important for this species than the current age of forest stand. Regardless of the indicative value, localities of both lichens within oak-hornbeam forests deserve the special protection status since they form unique assemblages of exclusive epiphytes, including those with high conservation value.

  10. Occupational noise in rice mills.

    PubMed

    Prasanna Kumar, G V; Dewangan, K N; Sarkar, Amaresh; Kumari, Amrita; Kar, Banani

    2008-01-01

    A major occupational hazard for the workers in rice mills is the noise during the operation of various machines. A noise survey was conducted in the workrooms of eight renowned rice mills of the north-eastern region of India established during the period between 1980 and 1985. The rice mills were selected on the basis of the outcome of a walk-through noise survey involving several rice mills of the region. A noise survey map of each rice mill was drawn to identify the predominant noise sources and the causes of high noise in the workrooms of the rice mill. The sound-pressure level (SPL) in the workrooms of the rice mill varied from 78 to 92 dBA. The paddy cleaner, rubber roll sheller, compartment separator, rice cleaner, auxiliary sieve shaker and an electric motor without enclosure were found to be the predominant noise sources in the workrooms of the mill. The causes of high noise in the rice mills may be attributed to the use of a long flat belt drive, crank-and-pitman mechanism, absence of an electric motor enclosure, poor machine maintenance and inadequate acoustic design of the workroom of the rice mill. About 26% of the total labourers were found to be exposed to higher levels of noise than 85 dBA. Subjective response indicated that about 26% of the total labourers felt noise interferes in their work and about 49% labourers were of opinion that noise interferes with their conversation. Noise from machines in the rice mills was found to be the major occupational hazard for the rice mill workers. The predominant noise sources need to be identified and the causes of high noise need to be studied to undertake the appropriate measures to reduce the noise level. To identify the predominant noise sources and their distributions in rice mills, to study the causes of high levels of noise in rice mills and to examine the response of the workers towards noise. A noise survey was conducted in eight renowned rice mills of the north-eastern region of India. The mills were

  11. Fingerprint of Seasonal Relative humidity in Rice (Oryza sativa L.): Potential for Paleoclimate Archive

    NASA Astrophysics Data System (ADS)

    Kaushal, R.; Ghosh, P.

    2015-12-01

    Seasonal variability of relative humidity (RH) condition during southwest monsoon (SWM) is strongly related with availability of moisture for rainfall over the continental region. There are ongoing efforts to reconstruct the past monsoonal condition based on geochemical and isotopic records as proxies [1]. However, limited archives have been successfully retrieved for reconstructing moisture condition during SWM [2]. Potential of plants as climate archives and the mechanism involved in transfer of climate signature to the stable isotope composition of oxygen (δ18O) has been demonstarted successfully [3]. Here we are introducing δ18O of rice grain bulk organic matter (δ18OOM) as a new proxy for precise determination of RH during SWM. Rice is a seasonal crop and widely cultivated over the Indian subcontinent during SWM. Here we present δ18OOM of rice grains collected from 15 locations from different climatic zones over the Indian subcontinent, ranging from semi-arid to humid-perhumid. These samples were collected from the harvest of the crop grown at the time of SWM for the period 2012-2014. Each of these climatic zones are characterized by unique range of RH values, which is expected to leave distinct oxygen isotopic signature in the rice grain OM. We compared the δ18OOM values with δ18O of precipitation water, RH and temperature during the period of cultivation. Precipitation δ18O values were obtained from were obtained from OPIC [4]. Our observations document a significant relationship between δ18OOM and RH (R2 =0.62, p<0.001). When the RH level fluctuated from 65% to 88%, δ18OOM tended to vary between 31.5 ‰ to 15.4‰. However, the humid regions with rainfed crop showed significant relationship between δ18OOM and precipitation δ18O. Remaining stations being fed by the both rain and irrigation from river/ groundwater, dampen the rainfall isotope signature in δ18OOM. This approach can be extended in deriving RH of regions of rice cultivation by

  12. Stealth quasi-circular depressions (sQCDs) in the northern lowlands of Mars

    NASA Astrophysics Data System (ADS)

    Buczkowski, Debra L.

    While QCDs are quasi-circular depressions revealed in the Mars Orbiter Laser Altimeter (MOLA) gridded data set, "stealth QCDs" (sQCDs) are those QCDs that have no obvious structural representation in visible images of Mars. It has been suggested that sQCDs are surface representations of buried impact craters, and on the basis of this assumption, size-frequency distributions of all QCDs in the northern lowlands have been constructed to date the buried lowland floor. Expanding upon previous studies of stealth QCDs around the Utopia Basin, 446 sQCDs with diameters ranging from 7 to 115 km have been identified in the northern lowlands of Mars. The direct relationship of sQCD surface relief to diameter indicates that stealth QCDs form due to differential compaction of a cover material over buried impact craters. A comparison of sQCD location to the geologic map of the northern lowlands reveals that stealth QCDs are only located in geologic units predicted to be capable of differential compaction, consistent with models of their formation. The slope of the trend of the sQCDs surface relief versus diameter has a coefficient of determination (R2) approaching 1, when sQCDs are evaluated by geologic unit and by regions of inferred comparable cover thickness. Trend-slope analysis also indicates that the lowland cover material is thickest in the Scandia region and the center of the Borealis and Utopia basins and thinnest in Isidis Planitia and north of Arabia Terra.

  13. Last Major Ice Collapse (17ka - 16ka) of the Anchorage Lowland, Alaska

    NASA Astrophysics Data System (ADS)

    Kopczynski, S. B.; Lowell, T.; Evenson, E. B.

    2009-12-01

    This research presents evidence describing the final ice collapse of the Anchorage Lowland of the Upper Cook Inlet, Alaska. A field research effort conducted with Richard Reger and the author analyzed over 14,000 drift pebble provenance samples to distinguish flow paths of this ice lobe composed of a twinned terrestrial glacier and tidewater glacier. Terrain geomorphological interpretations, 14 new basal lake radiocarbon ages, and a suite of previously collected radiocarbon ages are brought to bear to bracket ice retreat chronology. We interpret our evidence to argue that the Matanuska-Knik Lobe retreated between 16ka and 17ka by a coupled calving margin and ice stagnation collapse. The oldest age in the lowland is a basal age of 16.4ka collected on the Knik portion of the Elmendorf Moraine. Basal ages 140km away near the modern Matanuska Terminus indicate ice retreated to this position by 14.5ka. Two large esker swarms along the Matanuska route suggest evidence for a two phased terrestrial retreat. The Anchorage lowland retreat started well before the Bolling warming, though radiocarbon data and esker-swarm patterns suggest evidence for a two stepped retreat, with the second faster phase occurring during the Bolling. We find it curious that the onset of Anchorage Lowland ice retreat falls within the mystery interval and is concordant with retreat patterns at the Puget Lowland and the Des Moines Lobe.

  14. Herbivory and nutrient limitation protect warming tundra from lowland species' invasion and diversity loss.

    PubMed

    Eskelinen, Anu; Kaarlejärvi, Elina; Olofsson, Johan

    2017-01-01

    Herbivory and nutrient limitation can increase the resistance of temperature-limited systems to invasions under climate warming. We imported seeds of lowland species to tundra under factorial treatments of warming, fertilization, herbivore exclusion and biomass removal. We show that warming alone had little impact on lowland species, while exclusion of native herbivores and relaxation of nutrient limitation greatly benefitted them. In contrast, warming alone benefitted resident tundra species and increased species richness; however, these were canceled by negative effects of herbivore exclusion and fertilization. Dominance of lowland species was associated with low cover of tundra species and resulted in decreased species richness. Our results highlight the critical role of biotic and abiotic filters unrelated to temperature in protecting tundra under warmer climate. While scarcity of soil nutrients and native herbivores act as important agents of resistance to invasions by lowland species, they concurrently promote overall species coexistence. However, when these biotic and abiotic resistances are relaxed, invasion of lowland species can lead to decreased abundance of resident tundra species and diminished diversity.

  15. Accelerated Solvent Extraction of Insecticides from Rice Hulls, Rice Bran, and Polished Rice Grains.

    PubMed

    Teló, Gustavo Mack; Senseman, Scott Allen; Marchesan, Enio; Camargo, Edinalvo Rabaioli; Carson, Katherine

    2017-03-01

    Analysis of pesticide residues in irrigated rice grains is important for food security. In this study, we analyzed accelerated solvent extraction (ASE) conditions for the extraction of thiamethoxam and chlorantraniliprole insecticides from rice hulls, rice bran, and polished rice grains. Several variables, including extraction solvent, extraction temperature, extraction pressure, cell size, static extraction time, and sample concentration, were investigated. The average recoveries of the three matrixes were between 89.7 and 109.7% at the fortification level of 0.75 mg/kg. The optimum ASE operating conditions were acetonitrile (100%) as extraction solvent, extraction temperature of 75°C for rice hulls and 100°C for rice bran and polished rice grains, extraction cell pressure of 10.3 MPa, 22 mL cell size, and two extraction cycles. The total extraction time was approximately 25 min. The extracted volume was evaporated to dryness and the residues were redissolved in 2 mL acetonitrile after 1 min of vortex-shaking. Thiamethoxam and chlorantraniliprole were analyzed by ultra-HPLC with tandem MS. In conclusion, ASE in rice hulls, rice bran, and polished rice grains offers the possibility of a fast and simple method for obtaining a quantitative extraction of the studied pesticides.

  16. Soil moisture changes in two experimental sites in Eastern Spain. Irrigation versus rainfed orchards under organic farming

    NASA Astrophysics Data System (ADS)

    Azorin-Molina, Cesar; Vicente-Serrano, Sergio M.; Cerdà, Artemi

    2013-04-01

    Within the Soil Erosion and Degradation Research Group Experimental Stations, soil moisture is being researched as a key factor of the soil hydrology and soil erosion (Cerdà, 1995; Cerda, 1997; Cerdà 1998). This because under semiarid conditions soil moisture content plays a crucial role for agriculture, forest, groundwater recharge and soil chemistry and scientific improvement is of great interest in agriculture, hydrology and soil sciences. Soil moisture has been seeing as the key factor for plant photosynthesis, respiration and transpiration in orchards (Schneider and Childers, 1941) and plant growth (Veihmeyer and Hendrickson, 1950). Moreover, soil moisture determine the root growth and distribution (Levin et al., 1979) and the soil respiration ( Velerie and Orchard, 1983). Water content is expressed as a ratio, ranging from 0 (dry) to the value of soil porosity at saturation (wet). In this study we present 1-year of soil moisture measurements at two experimental sites in the Valencia region, Eastern Spain: one representing rainfed orchard typical from the Mediterranean mountains (El Teularet-Sierra de Enguera), and a second site corresponding to an irrigated orange crop (Alcoleja). The EC-5 soil moisture smart sensor S-SMC-M005 integrated with the field-proven ECH2O™ Sensor and a 12-bit A/D has been choosen for measuring soil water content providing ±3% accuracy in typical soil conditions. Soil moisture measurements were carried out at 5-minute intervals from January till December 2012. In addition, soil moisture was measured at two depths in each landscape: 2 and 20 cm depth - in order to retrieve a representative vertical cross-section of soil moisture. Readings are provided directly from 0 (dry) to 0.450 m3/m3 (wet) volumetric water content. The soil moisture smart sensor is conected to a HOBO U30 Station - GSM-TCP which also stored 5-minute temperature, relative humidity, dew point, global solar radiation, precipitation, wind speed and wind direction

  17. Impact of climate change on water balance components in Mediterranean rainfed olive orchards under tillage or cover crop soil management

    NASA Astrophysics Data System (ADS)

    Rodríguez-Carretero, María Teresa; Lorite, Ignacio J.; Ruiz-Ramos, Margarita; Dosio, Alessandro; Gómez, José A.

    2013-04-01

    The rainfed olive orchards in Southern Spain constitute the main socioeconomic system of the Mediterranean Spanish agriculture. These systems have an elevated level of complexity and require the accurate characterization of crop, climate and soil components for a correct management. It is common the inclusion of cover crops (usually winter cereals or natural cover) intercalated between the olive rows in order to reduce water erosion. Saving limited available water requires specific management, mowing or killing these cover crops in early spring. Thus, under the semi-arid conditions in Southern Spain the management of the cover crops in rainfed olive orchards is essential to avoid a severe impact to the olive orchards yield through depletion of soil water. In order to characterize this agricultural system, a complete water balance model has been developed, calibrated and validated for the semi-arid conditions of Southern Spain, called WABOL (Abazi et al., 2013). In this complex and fragile system, the climate change constitutes a huge threat for its sustainability, currently limited by the availability of water resources, and its forecasted reduction for Mediterranean environments in Southern Spain. The objective of this study was to simulate the impact of climate change on the different components of the water balance in these representative double cropping systems: transpiration of the olive orchard and cover crop, runoff, deep percolation and soil water content. Four climatic scenarios from the FP6 European Project ENSEMBLES were first bias corrected for temperatures and precipitation (Dosio and Paruolo, 2011; Dosio et al., 2012) and, subsequently, used as inputs for the WABOL model for five olive orchard fields located in Southern Spain under different conditions of crop, climate, soils and management, in order to consider as much as possible of the variability detected in the Spanish olive orchards. The first results indicate the significant effect of the cover

  18. Influence of N fertilization rates, rainfall, and temperature on nitrate leaching from a rainfed winter wheat field in Taihu watershed

    NASA Astrophysics Data System (ADS)

    Liang, Xin-Qiang; Xu, Lei; Li, Hua; He, Miao-Miao; Qian, Yi-Chao; Liu, Jin; Nie, Ze-Yu; Ye, Yu-Shi; Chen, Yingxu

    Cropland derived nitrate leaching was a major reason for groundwater pollution. The objective of this study was to on-farm investigate the behavior of nitrate leaching affected by N fertilization rates, rainfall, and temperature in a rainfed winter wheat field in Taihu watershed. The experiment had five urea-N rates (0-360 kg N ha -1 in 90-kg increments), and nitrate-N in leachate was daily collected by wedge-shaped fiberglass wick lysimeters during four stages (seeding stage, SS; tillering stage, TS; booting stage, BS; harvesting stage, HS). Results showed that: (1) higher potential of leachate would be engendered when the rainfall intensity was over 5.9 mm d -1; (2) variations of nitrate concentrations in leachate were well responsed to three split fertilizations, which increased with the increase of urea-N applied rates. A similar variation pattern of nitrate concentrations was observed in -0.3 m and -0.6 m soil leachate. Besides, the nitrate concentrations in leachate could be raised with the sharply increase of air temperature, especially in the SS and TS stages; (3) the fluxes of nitrate leaching were significantly affected by N rates ( P < 0.05) with the loss ratio varied from 4.0% to 8.5% for five treatments, and the fluxes in four wheat growing stages followed the order of TS > HS > BS > SS. The N application rate of 180 kg N ha -1 optimized wheat production, but N application over that rate greatly increased nitrate leaching potential. Therefore, options other than lowering the N application rate need to be considered to reduce environmental impacts while maintain winter wheat production.

  19. [Effects of different film mulch and ridge-furrow cropping patterns on yield formation and water translocation of rainfed potato].

    PubMed

    Qin, Shu-Hao; Zhang, Jun-Lian; Wang, Di; Pu, Yu-Lin; Du, Quan-Zhong

    2011-02-01

    This paper studied the effects of different film mulch and ridge-furrow cropping patterns on the yield formation and water translocation of rainfed potato in the semi-arid area of west Loess Plateau. Comparing with those under traditional harrowed bedding without film mulch (T1), the potato yield under harrowed bedding with film mulching (T2), completely mulched alternating narrow and wide ridges with furrow planting (T3), completely mulched alternating narrow and wide ridges with ridge planting (T4), mulched raised bedding with furrow planting (T5), and mulched raised bedding with bedding planting (T6) was increased by 50.1%, 75.9%, 86.8%, 69.6%, and 60. 6%, and the water use efficiency (WUE) was increased by 47.0%, 82.7%, 84.0%, 75.2%, and 54.3% respectively, with the increments being the highest under T4 and T3. All the film much and ridge-furrow cropping patterns improved the yield component of potato, and T4 and T3 were most beneficial to the increase of mid and big tubers, tuber number per plant, and tuber yield per plant, and to the decrease of the proportions of green and blet tubers. It was concluded that completely mulched alternating narrow and wide ridges with ridge planting (T4) and completely mulched alternating narrow and wide ridges with furrow planting (T3) were the two better cropping patterns in water-saving and high yielding for potato cultivation in semiarid areas.

  20. Awns reduce grain number to increase grain size and harvestable yield in irrigated and rainfed spring wheat

    PubMed Central

    Rebetzke, G. J.; Bonnett, D. G.; Reynolds, M. P.

    2016-01-01

    Genotypic variation in ear morphology is linked to differences in photosynthetic potential to influence grain yield in winter cereals. Awns contribute to photosynthesis, particularly under water-limited conditions when canopy assimilation is restricted. We assessed performance of up to 45 backcross-derived, awned–awnletted NILs representing four diverse genetic backgrounds in 25 irrigated or rainfed, and droughted environments in Australia and Mexico. Mean environment grain yields were wide-ranging (1.38–7.93 t ha−1) with vegetative and maturity biomass, plant height, anthesis date, spike number, and harvest index all similar (P >0.05) for awned and awnletted NILs. Overall, grain yields of awned–awnletted sister-NILs were equivalent, irrespective of yield potential and genetic background. Awnletted wheats produced significantly more grains per unit area (+4%) and per spike (+5%) reflecting more fertile spikelets and grains in tertiary florets. Increases in grain number were compensated for by significant reductions in grain size (–5%) and increased frequency (+0.8%) of small, shrivelled grains (‘screenings’) to reduce seed-lot quality of awnletted NILs. Post-anthesis canopies of awnletted NILs were marginally warmer over all environments (+0.27 °C) but were not different and were sometimes cooler than awned NILs at cooler air temperatures. Awns develop early and represented up to 40% of total spikelet biomass prior to ear emergence. We hypothesize that the allocation of assimilate to large and rapidly developing awns decreases spikelet number and floret fertility to reduce grain number, particularly in distal florets. Individual grain size is increased to reduce screenings and to increase test weight and milling quality, particularly in droughted environments. Despite the average reduction in grain size, awnless lines could be identified that combined higher grain yield with larger grain size, increased grain protein concentration, and reduced

  1. Effects of conservation tillage practices on ammonia emissions from Loess Plateau rain-fed winter wheat fields

    NASA Astrophysics Data System (ADS)

    Yang, Yang; Zhou, Chunju; Li, Na; Han, Kun; Meng, Yuan; Tian, Xiaoxiao; Wang, Linquan

    2015-03-01

    Ammonia emissions from agricultural activities contribute to air pollution. For the rain-fed winter wheat system in the Loess Plateau there is a lack of information about ammonia emissions. Current study aimed to provide field data on ammonia emissions affected by conservation tillage practices and nitrogen applications. A two-year field experiment was conducted during 2011-2013 wheat growing seasons followed a split-plot design. Main plots consisted of one conventional tillage (CT, as the control) and five conservation tillage systems, i.e., stalk mulching (SM), film mulching (FM), ridge tillage (RT), ridge tillage with film mulch on the ridge (RTfm), and ridge tillage with film mulch on the ridge and stalk mulch in the furrow (RTfmsm); while subplots consisted of two nitrogen application rates, i.e., 0 and 180 kg N ha-1. Ammonia emissions were measured using an acid trapping method with vented chambers. Results showed ammonia fluxes peaked during the first 10 days after fertilization. On average, nitrogen application increased ammonia emissions by 26.5% (1.31 kg N ha-1) compared with treatments without nitrogen application (P < 0.05). Ammonia fluxes were strongly dependent on soil ammonium, moisture, and temperature. Tillage systems had significant effects on ammonia emissions. On average, conservation tillage practices reduced ammonia emissions by 7.7% (0.46 kg N ha-1) compared with conventional tillage (P < 0.05), with FM most effective. Deep-band application of nitrogen fertilizer, stalk mulches, and film mulches were responsible for reductions in ammonia emissions from nitrogen fertilization in conservation tillage systems, thus they were recommended to reduce ammonia emissions from winter wheat production regions in the southern Loess Plateau.

  2. QTL mapping for nine drought-responsive agronomic traits in bread wheat under irrigated and rain-fed environments.

    PubMed

    Gahlaut, Vijay; Jaiswal, Vandana; Tyagi, Bhudeva S; Singh, Gyanendra; Sareen, Sindhu; Balyan, Harindra S; Gupta, Pushpendra Kumar

    2017-01-01

    In bread wheat, QTL interval mapping was conducted for nine important drought responsive agronomic traits. For this purpose, a doubled haploid (DH) mapping population derived from Kukri/Excalibur was grown over three years at four separate locations in India, both under irrigated and rain-fed environments. Single locus analysis using composite interval mapping (CIM) allowed detection of 98 QTL, which included 66 QTL for nine individual agronomic traits and 32 QTL, which affected drought sensitivity index (DSI) for the same nine traits. Two-locus analysis allowed detection of 19 main effect QTL (M-QTL) for four traits (days to anthesis, days to maturity, grain filling duration and thousand grain weight) and 19 pairs of epistatic QTL (E-QTL) for two traits (days to anthesis and thousand grain weight). Eight QTL were common in single locus analysis and two locus analysis. These QTL (identified both in single- and two-locus analysis) were distributed on 20 different chromosomes (except 4D). Important genomic regions on chromosomes 5A and 7A were also identified (5A carried QTL for seven traits and 7A carried QTL for six traits). Marker-assisted recurrent selection (MARS) involving pyramiding of important QTL reported in the present study, together with important QTL reported earlier, may be used for improvement of drought tolerance in wheat. In future, more closely linked markers for the QTL reported here may be developed through fine mapping, and the candidate genes may be identified and used for developing a better understanding of the genetic basis of drought tolerance in wheat.

  3. Amended final report on the safety assessment of Oryza Sativa (rice) Bran Oil, Oryza Sativa (rice) Germ Oil, Rice Bran Acid,Oryza Sativa (rice) Bran Wax, Hydrogenated Rice Bran Wax, Oryza Sativa (rice)Bran Extract, Oryza Sativa (rice) Extract, Oryza Sativa (rice) Germ Powder, Oryza Sativa (rice) Starch, Oryza Sativa (rice) Bran, Hydrolyzed Rice Bran Extract, Hydrolyzed Rice Bran Protein, Hydrolyzed Rice Extract, and Hydrolyzed Rice Protein.

    PubMed

    2006-01-01

    This report addresses the safety of cosmetic ingredients derived from rice, Oryza sativa. Oils, Fatty Acids, and Waxes: Rice Bran Oil functions in cosmetics as a conditioning agent--occlusive in 39 formulations across a wide range of product types. Rice Germ Oil is a skin-conditioning agent--occlusive in six formulations in only four product categories. Rice Bran Acid is described as a surfactant-cleansing agent, but was not in current use. Rice Bran Wax is a skin-conditioning agent--occlusive in eight formulations in five product categories. Industry did not directly report any use of Rice Bran Wax. Hydrogenated Rice Bran Wax is a binder, skin-conditioning agent--occlusive, and viscosity-increasing agent--nonaqueous in 11 formulations in six product categories. Rice Bran Oil had an oral LD50 of > 5 g/kg in white rats and Rice Wax had an oral LD50 of > 24 g/kg in male mice. A three-generation oral dosing study reported no toxic or teratologic effects in albino rats fed 10% Rice Bran Oil compared to a control group fed Peanut Oil. Undiluted Rice Bran Oil, Rice Germ Oil, and Hydrogenated Rice Bran Wax were not irritants in animal skin tests. Rice Bran Oil was not a sensitizer. Rice Bran Oil, Rice Germ Oil, Rice Wax, and Hydrogenated Rice Bran Wax were negative in ocular toxicity assays. A mixture of Rice Bran Oil and Rice Germ Oil had a ultraviolet (UV) absorption maximum at 315 nm, but was not phototoxic in a dermal exposure assay. Rice Bran Oil was negative in an Ames assay, and a component, gamma-oryzanol, was negative in bacterial and mammalian mutagenicity assays. Rice oils, fatty acids, and waxes were, at most, mildly irritating in clinical studies. Extracts: Rice Bran Extract is used in six formulations in four product categories. Rice Extract is a hair-conditioning agent, but was not in current use. Hydrolyzed Rice Extract is used in four formulations and current concentration of use data were provided for other uses. Hydrolyzed Rice Bran Extract, described

  4. Global warming, elevational range shifts, and lowland biotic attrition in the wet tropics.

    PubMed

    Colwell, Robert K; Brehm, Gunnar; Cardelús, Catherine L; Gilman, Alex C; Longino, John T

    2008-10-10

    Many studies suggest that global warming is driving species ranges poleward and toward higher elevations at temperate latitudes, but evidence for range shifts is scarce for the tropics, where the shallow latitudinal temperature gradient makes upslope shifts more likely than poleward shifts. Based on new data for plants and insects on an elevational transect in Costa Rica, we assess the potential for lowland biotic attrition, range-shift gaps, and mountaintop extinctions under projected warming. We conclude that tropical lowland biotas may face a level of net lowland biotic attrition without parallel at higher latitudes (where range shifts may be compensated for by species from lower latitudes) and that a high proportion of tropical species soon faces gaps between current and projected elevational ranges.

  5. Towards a better understanding of water partitioning processes for improved smallholder rainfed agricultural systems: A case study of Makanya catchment, Tanzania

    NASA Astrophysics Data System (ADS)

    Makurira, H.; Savenije, H. H. G.; Uhlenbrook, S.; Rockström, J.; Senzanje, A.

    Water shortage in agricultural systems has led to low crop water productivity in various farming systems. For smallholder rainfed systems, dry spell occurrences during seasons and in between seasons has severely undermined food security and general livelihoods as the majority of populations, particularly in sub-Saharan Africa, derive their livelihoods solely from rainfed agriculture. This paper presents part of the on-going research to better understand the hydrology and hence improve rainfed water productivity in arid and semi-arid regions. The study showed that rainwater alone is not sufficient to support maize which is the preferred staple food crop hence the need to employ a combination of improved tillage and rainwater harvesting techniques which help to boost crop yields. The study showed that with as little rainfall as 186-403 mm/season yields of up to 4.8 t ha -1 can be achieved through the application of more efficient soil and water retention techniques compared to much less than 1 t ha -1 as presently achieved. It was concluded that water is the limiting factor to productivity and that a combination of rainwater harvesting and conservation agriculture can contribute to improved grain yields by as much as 80%. There was no significant improvement to treatments with manure and/or cover crop. Water availability indeed plays a significant role in the yields realised. The challenge then is to better understand how, at field scale, the existing water partitioning process can be altered to channel more water into the productive green water processes at the expense of the non-productive white and green water fluxes.

  6. qDTY12.1: a locus with a consistent effect on grain yield under drought in rice

    PubMed Central

    2013-01-01

    Background Selection for grain yield under drought is an efficient criterion for improving the drought tolerance of rice. Recently, some drought-tolerant rice varieties have been developed using this selection criterion and successfully released for cultivation in drought-prone target environments. The process can be made more efficient and rapid through marker-assisted breeding, a well-known fast-track approach in crop improvement. QTLs have been identified for grain yield under drought with large effects against drought-susceptible varieties. Most of the identified QTLs show large QTL × environment or QTL × genetic background interactions. The development of mapping populations in the background of popular high-yielding varieties, screening across environments, including the target environments, and the identification of QTLs with a consistent effect across environments can be a suitable alternative marker-assisted breeding strategy. An IR74371-46-1-1 × Sabitri backcross inbred line population was screened for reproductive-stage drought stress at the International Rice Research Institute, Philippines, and Regional Agricultural Research Station, Nepalgunj, Nepal, in the dry and wet seasons of 2011, respectively. A bulk segregant analysis approach was used to identify markers associated with high grain yield under drought. Results A QTL, qDTY12.1, significantly associated with grain yield under reproductive-stage drought stress was identified on chromosome 12 with a consistent effect in two environments: IRRI, Philippines, and RARS, Nepalgunj, Nepal. This QTL explained phenotypic variance of 23.8% and contributed an additive effect of 45.3% for grain yield under drought. The positive QTL allele for qDTY12.1 was contributed by tolerant parent IR74371-46-1-1. Conclusions In this study, qDTY12.1 showed a consistent effect across environments for high grain yield under lowland reproductive-stage drought stress in the background of popular high

  7. Spatial Variability of Streambed Hydraulic Conductivity of a Lowland River

    NASA Astrophysics Data System (ADS)

    Schneidewind, Uwe; Thornton, Steven; Van De Vijver, Ellen; Joris, Ingeborg; Seuntjens, Piet

    2015-04-01

    Streambed hydraulic conductivity K is a key physical parameter, which describes flow processes in the hyporheic zone (HZ), i.e. the dynamic interface between aquifers and streams or rivers. Knowledge of the spatial variability of K is also important for the interpretation of contaminant transport processes in the HZ. Streambed K can vary over several magnitudes at small spatial scales. It depends mostly on streambed sediment characteristics (e.g. effective porosity, grain size, packing), streambed processes (e.g. sedimentation, colmation and erosion) and the development of stream channel geometry and streambed morphology (e.g. dunes, anti-dunes, pool-riffle sequences, etc.). Although heterogeneous in natural streambeds, streambed K is often considered to be a constant parameter due to a lack of information on its spatial distribution. Here we show the spatial variability of streambed K for a small section of the River Tern, a lowland river in the UK. Streambed K was determined for more than 120 vertically and horizontally distributed locations from grain size analyses using four empirical approaches (Hazen, Beyer, Kozeny and the USBR model). Additionally, streambed K was estimated from falling head tests in 36 piezometers installed into the streambed on a 4 m by 16 m grid, by applying the Springer-Gelhar Model. For both methods streambed K followed a log-normal distribution. Variogram analysis was used to deduce the spatial variability of the streambed K values within several streambed profiles parallel and perpendicular to the main flow direction in the stream. Hydraulic conductivity Kg estimated from grain size analyses varied between 1 m/d and 155 m/d with standard deviations of 79% to 99% depending on the empirical approach used. Kh estimated from falling head tests varied between 1 m/d and 22 m/d with a standard deviation of about 50%, depending on the degree of anisotropy assumed. After rescaling the data to obtain a common sample support, Pearson correlation

  8. Early Holocene lake ecosystem development in the southern Baltic lowlands

    NASA Astrophysics Data System (ADS)

    Słowiński, Michał; Ott, Florian; Kramkowski, Mateusz; Noryśkiewicz, Agnieszka M.; Zawiska, Izabela; Dräger, Nadine; Theuerkauf, Martin; Hass, Christoph; Obremska, Milena; Błaszkiewicz, Mirosław; Kordowski, Jarosław; Tjallingii, Rik; Rzodkiewicz, Monika; Schwab, Markus; Brauer, Achim

    2016-04-01

    The first millennia of the Holocene are characterized by gradual and rapid environmental changes following the warming at the beginning of the Holocene superimposed by short-term climatic instability. Landscape evolution during this period occurred at different time scales due to specific response times of landscape compartments like vegetation succession, soil formation and permafrost thawing. As a consequence, a spatiotemporally heterogeneous pattern of changes occurred particularly in regions close to the margins of the continental ice sheets like the Baltic region. Regional atmospheric circulation patterns were affected by cold catabatic winds from the remains of the Fennoscandian ice sheet. The ongoing deglaciation further influenced the regional climate through meltwater release and related changes in the North Atlantic thermohaline circulation. Both effects declined with the progressive ice sheet melt down. Additionally, the land-sea distribution in the North Sea changed drastically during the final melting phase of the glacial ice sheets. The Baltic Sea development is even more complex due to the strong glacio-isostatic adjustments effects that resulted in open and closed water stages affecting the entire Baltic realm. Consequently, the early Holocene interval of sediment records from the southern Baltic lowlands are not considered as straightforward palaeoclimate archives but need to be interpreted in a broader context. We present five partly varved lake records from northern Poland all including an intriguing highly organic-rich interval interrupting biochemical calcite precipitation at about the same time between 10.5 and 10.2 cal kyr BP. These sediment records have been correlated by independent age models based on varve counting, AMS 14C dating, biostratigraphy and tephrochronology. We present multi-proxy records of early Holocene sediments and our preliminary interpretation suggests hydrological processes as the main reason for the intriguing shifts

  9. Earth observing data and methods for advancing water harvesting technologies in the semi-arid rain-fed environments of India

    USGS Publications Warehouse

    Sharma, C.; Thenkabail, P.; Sharma, R. R.

    2011-01-01

    The paper develops approaches and methods of modeling and mapping land and water productivity of rain-fed crops in semi-arid environments of India using hyperspectral, hyperspatial, and advanced multispectral remote sensing data and linking the same to field-plot data and climate station data. The overarching goal is to provide information to advance water harvesting technologies in the agricultural croplands of the semi-arid environments of India by conducting research in a representative pilot site in Jodhpur, Rajasthan, India. ?? 2011 IEEE.

  10. A long pollen record from lowland Amazonia: Forest and cooling in glacial times

    SciTech Connect

    Colinvaux, P.A.; Moreno, J.E.; Bush, M.B.

    1996-10-04

    A continuous pollen history of more than 40,000 years was obtained from a lake in the lowland Amazon rain forest. Pollen spectra demonstrate that tropical rain forest occupied the region continuously and that savannas or grasslands were not present during the last glacial maximum. The data suggest that the western Amazon forest was not fragmented into refugia in glacial times and that the lowlands were not a source of dust. Glacial age forests were comparable to modern forests but also included species now restricted to higher evaluations by temperature, suggesting a cooling of the order of 5{degrees} to 6{degrees}C. 23 refs., 22 tabs.

  11. Linking large-scale bean-rice rotation with increased rice yield in remote sensing experiment

    NASA Astrophysics Data System (ADS)

    Sun, Ling; Zhu, Zesheng

    2017-08-01

    In this study, the two different treatments are continuous rice and rice in rotation with bean, and the response is the normalized difference vegetation index (NDVI) of rice or the rice yield. This study is to determine whether the rice in rotation with bean results in a significant effect—increasing the rice yield. In this completely randomized experiment, we randomly assigned 40 samples to the continuous rice and 40 samples to the rice in rotation with bean. Then the rice NDVIs of all 80 samples were computed. Because the statistical significance of the rice NDVI of the rotation treatment was observed in the experiment, we can be confident in the conclusion that it was the difference in treatments that resulted in the difference in the rice yield. That is, we can be confident that a cause-and-effect relationship between the rice in rotation with bean and the rice yield increase has been found.

  12. Tissue Localization of a Submergence-Induced 1-Aminocyclopropane-1-Carboxylic Acid Synthase in Rice1

    PubMed Central

    Zhou, Zhongyi; de Almeida Engler, Janice; Rouan, Dominique; Michiels, Frank; Van Montagu, Marc; Van Der Straeten, Dominique

    2002-01-01

    At least two 1-aminocyclopropane-1-carboxylic acid synthase genes (ACS) are implicated in the submergence response of rice (Oryza sativa). Previously, the OS-ACS5 gene has been shown to be induced during short- as well as long-term complete submergence of seedlings and to be controlled by a balance of gibberellin and abscisic acid in both lowland and deepwater rice. This study demonstrates that OS-ACS5 mRNA is localized in specific tissues and cells both during normal development and in response to complete submergence. The temporal and spatial regulation of OS-ACS5 expression is presented by in situ hybridization and histochemical analysis of β-glucuronidase (GUS) activity in transgenic rice carrying an OS-ACS5-gus fusion. Whole-mount in situ hybridization revealed that in air-grown rice seedlings, OS-ACS5 was expressed at a low level in the shoot apex, meristems, leaf, and adventitious root primordia, and in vascular tissues of nonelongated stems and leaf sheaths. In response to complete submergence, the expression in vascular bundles of young stems and leaf sheaths was strongly induced. The results of histochemical GUS assays were consistent with those found by whole-mount in situ hybridization. Our findings suggest that OS-ACS5 plays a role in vegetative growth of rice under normal conditions and is also recruited for enhanced growth upon complete submergence. The possible implication of OS-ACS5 in root-shoot communication during submergence stress and its putative role in aerenchyma formation upon low-oxygen stress are discussed. PMID:12011339

  13. Maximum outcrossing rate and genetic compatibility between red rice (Oryza sativa) biotypes and Clearfield™ rice

    USDA-ARS?s Scientific Manuscript database

    Although red rice can be selectively controlled with imazethapyr in ClearfieldTM (CL) rice, the transfer of the imazethapyr-resistant gene from CL rice to red rice is an ecological risk. Previous experiments indicated that flowering synchronization and genetic compatibility between cultivated rice a...

  14. Outcrossing Potential between U.S. Blackhull Red Rice and Indica Rice Cultivars

    USDA-ARS?s Scientific Manuscript database

    Weedy red rice is a major weed pest of rice in the southern U.S. Outcrossing between red rice and commercial tropical japonica rice cultivars has resulted in new weed biotypes that further hinder the effectiveness of weed management. In recent years, indica rice has been used increasingly as a ger...

  15. Elicitor-Induced Biochemical and Molecular Manifestations to Improve Drought Tolerance in Rice (Oryza sativa L.) through Seed-Priming

    PubMed Central

    Samota, Mahesh K.; Sasi, Minnu; Awana, Monika; Yadav, Om P.; Amitha Mithra, S. V.; Tyagi, Aruna; Kumar, Suresh; Singh, Archana

    2017-01-01

    Rice (Oryza sativa L.) is one of the major grain cereals of the Indian subcontinent which face water-deficit stress for their cultivation. Seed-priming has been reported to be a useful approach to complement stress responses in plants. In the present study, seed-priming with hormonal or chemical elicitor [viz. methyl jasmonate (MJ), salicylic acid (SA), paclobutrazol (PB)] showed significant increase in total phenolic content, antioxidant activity and expression of Rice Drought-responsive (RD1 and RD2) genes (of AP2/ERF family) in contrasting rice genotypes (Nagina-22, drought-tolerant and Pusa Sugandh-5, drought-sensitive) under drought stress. However, decrease in lipid peroxidation and protein oxidation was observed not only under the stress but also under control condition in the plants raised from primed seeds. Expression analyses of RD1 and RD2 genes showed upregulated expression in the plants raised from primed seeds under drought stress. Moreover, the RD2 gene and the drought-sensitive genotype showed better response than that of the RD1 gene and the drought-tolerant genotype in combating the effects of drought stress. Among the elicitors, MJ was found to be the most effective for seed-priming, followed by PB and SA. Growth and development of the plants raised from primed seeds were found to be better under control and drought stress conditions compared to that of the plants raised from unprimed seeds under the stress. The present study suggests that seed-priming could be one of the useful approaches to be explored toward the development of simple, cost-effective and farmer-friendly technology to enhance rice yield in rainfed areas. PMID:28634483

  16. The plot size effect on soil erosion on rainfed agriculture land under different land uses in eastern Spain

    NASA Astrophysics Data System (ADS)

    Cerdà, A.; Bodí, M. B.; Burguet, M.; Segura, M.; Jovani, C.

    2009-04-01

    at the smallest plots what demonstrated a relevant contribution of the reinfiltration of the surface runoff. The proportion of rainfall that was transformed into runoff decreased with increasing plot size. There was not a clear variation in sediment concentrations with plot size, but soil erosion rates were generally higher on the smaller plots. Key words: Scale, Soil, Erosion, Spain, Land Management, Slope, Agriculture, Rainfed.

  17. [Characteristics of dry matter and potassium accumulation and distribution in potato plant in semi-arid rainfed areas].

    PubMed

    Lu, Jian-Wu; Qiu, Hui-Zhen; Zhang, Wen-Ming; Wang, Di; Zhang, Jun-Lian; Zhang, Chun-Hong; Hou, Shu-Yin

    2013-02-01

    In 2010, a field experiment with potato (Solanum tuberosum) cultivar 'Xindaping' was conducted at the Dingxi Extension Center of Gansu Province, Northwest China, aimed to understand the accumulation and distribution patterns of dry matter (DM) and potassium (K) in the organs of potato plant in semi-arid rainfed areas. During the whole growth period of the cultivar, the DM accumulation in root, stem, and leaf all showed a unimodal curve, with the DM accumulation rate being leaf > stem > root, whereas the DM accumulation in whole plant and tuber was an S-curve. The maximum DM accumulation rate of the whole plant was higher than that of the tuber, and appeared 17 days earlier. The distribution of DM in different organs showed two turning points, i.e., during the tuber formation (TF) period and the tuber growth (TG) period. During TF period, the DM accumulation was the greatest in leaf, followed by in tuber. The TF period was also the DM balance period, which occurred 90 days after emergence. Before the DM balance period, the DM accumulation in tuber was lesser than that in root, stem, and leaf, and there was a positive correlation between the DM accumulation in tuber and in root, stem, and leaf. However, after the DM balance period, the DM accumulation in tuber was greater than that in root, stem, and leaf, and the correlation was negative. At seedling stage and in TF period, TG period, starch accumulation period, and maturity period, the DM accumulation in whole plant was 5%, 30%, 60%, 4% , and 1%, while that in tuber was 0,18% , 62 , 18% , and 2%, respectively. In the whole growth period, more than 50% of the DM was formed in TG period. The K concentration was the highest in stem and the lowest in tuber, though the K was mostly concentrated in root before the DM balance period. The K accumulation before the DM balance period was mostly in root, stem, and leaf, with the sequence of stem > leaf > root, but after the DM balance period, the K was mainly allocated in

  18. Hazards Associated with High Altitude Rain-Fed Lakes (HARL) in the Overdeepened Deglaciated Region of Hindu Kush and Himalaya

    NASA Astrophysics Data System (ADS)

    Haritashya, U. K.; Hess, T. G.

    2014-12-01

    Mountain regions are changing rapidly as a result of climate change. It has been well established that these mountain regions are experiencing rapid glacier retreat. With accelerated retreat, glacial melt runoff can accumulate in an overdeepened glacier bed left behind by the receding glacier and can be bound by the walls of unstable frontal and lateral moraines to form a hazardous lake. However, when smaller glaciers retreat and downwaste they no longer contain enough ice to sustain the flow of water and maintain level of the lake. Furthermore, some smaller glaciers in the Hindu Kush and Himalayan region are observing extreme downwasting, which are either turning them into a rock glacier or heavily debris covered glacier leading to the reduced ice melt. Consequently, it is important to study these overdeepened beds, which are contained by the unstable mass. This is especially significant considering the great degree of complexity in the mountain weather system and recent examples of high intensity and short duration rainfall in the Hindu Kush region of Afghanistan, Karakoram region of Pakistan, and Central Himalayan region of India and Nepal. A precise understanding of mountain climate system is necessary, but so does these potentially deglaciated overdeepened beds where rain-fed lakes can form and increase systems hydrostatic pressure that can breach moraine containment and flood entire downstream region. Once lake has formed it possesses hydrological characteristics that are similar to the glacial lakes, which are known to put lives and infrastructure in danger. Therefore, in this study we evaluated overdeepened beds that are located in the complex topography and contained by abandoned or unstable lateral moraine using field and remote sensing satellite images. Our results provide degree of failure associated with these lakes based on the complex spatial and topological analysis as well as orographic distribution of the region. Such studies are not common in the

  19. Effect of Sowing Methods and NPK Levels on Growth and Yield of Rainfed Maize (Zea mays L.)

    PubMed Central

    2015-01-01

    To investigate the response of rainfed maize to sowing methods and NPK levels, an experiment was undertaken during kharif of 2011 and 2012 at Dryland (Kerawa) Agriculture Research Station, Sher-e-Kashmir University of Agricultural Sciences and Technology of Kashmir, Budgam. The experiment was laid out in a randomized block design with combination of 2 sowing methods (flat sowing, 75 cm apart rows, and ridge sowing, 75 cm apart ridges) and 3 fertility levels (60 : 40 : 20, 75 : 50 : 30, and 90 : 60 : 40 N : P2O5 : K2O kg ha−1) with three replications. Various growth characters, namely, plant height, leaf area index, dry matter accumulation, number of days to different phenological stages, and yield, and yield contributing characters namely, cob length, number of grains cob−1, cob diameter (cm), and 100-seed weight (g), were significantly higher with S2 over S1 during both the years of experimentation. Fertilizer levels F3 (90 : 60 : 40) and F2 (75 : 50 : 30) at par with one another produced significant increase in growth and yield characters, namely, plant height, leaf area index, dry matter production at different growth stages, cob length, number of cobs plant−1, number of grains cob−1, and 100-seed weight over F1 (60 : 40 : 20). Significantly higher grain yield was recorded with fertilizer level F3 (90 : 60 : 40) being at par with F2 (75 : 50 : 30) and showed significant increase over F1 (60 : 40 : 20) with superiority of 5.4 and 5.7 per cent during 2011 and 2012, respectively. The findings of the study concluded that ridge method of sowing of maize with NPK levels of 75 : 50 : 30 kg ha−1 showed better performance of crop in terms of growth, yield, and yield attributes. PMID:26090269

  20. Effect of Sowing Methods and NPK Levels on Growth and Yield of Rainfed Maize (Zea mays L.).

    PubMed

    Gul, Shamim; Khan, M H; Khanday, B A; Nabi, Sabeena

    2015-01-01

    To investigate the response of rainfed maize to sowing methods and NPK levels, an experiment was undertaken during kharif of 2011 and 2012 at Dryland (Kerawa) Agriculture Research Station, Sher-e-Kashmir University of Agricultural Sciences and Technology of Kashmir, Budgam. The experiment was laid out in a randomized block design with combination of 2 sowing methods (flat sowing, 75 cm apart rows, and ridge sowing, 75 cm apart ridges) and 3 fertility levels (60 : 40 : 20, 75 : 50 : 30, and 90 : 60 : 40 N : P2O5 : K2O kg ha(-1)) with three replications. Various growth characters, namely, plant height, leaf area index, dry matter accumulation, number of days to different phenological stages, and yield, and yield contributing characters namely, cob length, number of grains cob(-1), cob diameter (cm), and 100-seed weight (g), were significantly higher with S2 over S1 during both the years of experimentation. Fertilizer levels F3 (90 : 60 : 40) and F2 (75 : 50 : 30) at par with one another produced significant increase in growth and yield characters, namely, plant height, leaf area index, dry matter production at different growth stages, cob length, number of cobs plant(-1), number of grains cob(-1), and 100-seed weight over F1 (60 : 40 : 20). Significantly higher grain yield was recorded with fertilizer level F3 (90 : 60 : 40) being at par with F2 (75 : 50 : 30) and showed significant increase over F1 (60 : 40 : 20) with superiority of 5.4 and 5.7 per cent during 2011 and 2012, respectively. The findings of the study concluded that ridge method of sowing of maize with NPK levels of 75 : 50 : 30 kg ha(-1) showed better performance of crop in terms of growth, yield, and yield attributes.

  1. Arsenic uptake in organic rice production systems

    USDA-ARS?s Scientific Manuscript database

    Arsenic in rice is known to be a problem in some rice-producing countries that have high levels of inorganic arsenic naturally occurring in water resources. However, it was never considered an issue for USA produced rice until international market surveys were published, indicating some USA rice sam...

  2. Rice Root Architectural Plasticity Traits and Genetic Regions for Adaptability to Variable Cultivation and Stress Conditions.

    PubMed

    Sandhu, Nitika; Raman, K Anitha; Torres, Rolando O; Audebert, Alain; Dardou, Audrey; Kumar, Arvind; Henry, Amelia

    2016-08-01

    Future rice (Oryza sativa) crops will likely experience a range of growth conditions, and root architectural plasticity will be an important characteristic to confer adaptability across variable environments. In this study, the relationship between root architectural plasticity and adaptability (i.e. yield stability) was evaluated in two traditional × improved rice populations (Aus 276 × MTU1010 and Kali Aus × MTU1010). Forty contrasting genotypes were grown in direct-seeded upland and transplanted lowland conditions with drought and drought + rewatered stress treatments in lysimeter and field studies and a low-phosphorus stress treatment in a Rhizoscope study. Relationships among root architectural plasticity for root dry weight, root length density, and percentage lateral roots with yield stability were identified. Selected genotypes that showed high yield stability also showed a high degree of root plasticity in response to both drought and low phosphorus. The two populations varied in the soil depth effect on root architectural plasticity traits, none of which resulted in reduced grain yield. Root architectural plasticity traits were related to 13 (Aus 276 population) and 21 (Kali Aus population) genetic loci, which were contributed by both the traditional donor parents and MTU1010. Three genomic loci were identified as hot spots with multiple root architectural plasticity traits in both populations, and one locus for both root architectural plasticity and grain yield was detected. These results suggest an important role of root architectural plasticity across future rice crop conditions and provide a starting point for marker-assisted selection for plasticity.

  3. Hydraulic Properties of Rice and the Response of Gas Exchange to Water Stress1

    PubMed Central

    Stiller, Volker; Lafitte, H. Renee; Sperry, John S.

    2003-01-01

    We investigated the role of xylem cavitation, plant hydraulic conductance, and root pressure in the response of rice (Oryza sativa) gas exchange to water stress. In the field (Philippines), the percentage loss of xylem conductivity (PLC) from cavitation exceeded 60% in leaves even in watered controls. The PLC versus leaf water potential relationship indicated diurnal refilling of cavitated xylem. The leaf water potential causing 50 PLC (P50) was –1.6 MPa and did not differ between upland versus lowland rice varieties. Greenhouse-grown varieties (Utah) were more resistant to cavitation with a 50 PLC of –1.9 MPa but also showed no difference between varieties. Six-day droughts caused concomitant reductions in leaf-specific photosynthetic rate, leaf diffusive conductance, and soil-leaf hydraulic conductance that were associated with cavitation-inducing water potentials and the disappearance of nightly root pressure. The return of root pressure after drought was associated with the complete recovery of leaf diffusive conductance, leaf-specific photosynthetic rate, and soil-leaf hydraulic conductance. Root pressure after the 6-d drought (61.2 ± 8.8 kPa) was stimulated 7-fold compared with well-watered plants before drought (8.5 ± 3.8 kPa). The results indicate: (a) that xylem cavitation plays a major role in the reduction of plant hydraulic conductance during drought, and (b) that rice can readily reverse cavitation, possibly aided by nocturnal root pressure. PMID:12857848

  4. Alluvial deposits and plant distribution in an Amazonian lowland megafan

    NASA Astrophysics Data System (ADS)

    Zani, H.; Rossetti, D.; Cremon; Cohen, M.; Pessenda, L. C.

    2012-12-01

    more pronounced after de mid-Holocene, suggesting that the open vegetation, represented mostly by C4 land plants, evolved only more recently. Based on our isotope data, a model is proposed taking into account the influence of sedimentary dynamics on the modern pattern of plan distribution. The establishment of open vegetation occurred at different times depending on location over the megafan area, varying from around 3,000 to 6,400 cal yrs BP. As sedimentation took place, areas located far from the surrounding rainforest were prone to inputs of organic matter derived from open vegetation, whereas the contribution of organic matter derived from arboreous vegetation increases toward the areas located closer to the rainforest. In general, open vegetation is constrained to depositional sites that remained active until relatively recent Holocene times, while surrounding areas with a relatively older geological history are covered by dense forest. The results presented here consist in a striking example of the influence of sedimentary processes during the Late Pleistocene-Holocene on the development of modern plants of this Amazonian lowland.

  5. A comparison of water use and water-use-efficiency of maize and biomass sorghum in the rain-fed, Midwestern, US.

    NASA Astrophysics Data System (ADS)

    Roby, M.; Salas Fernandez, M.; VanLoocke, A. D.

    2014-12-01

    There is growing consensus among model projections that climate change may increase the frequency and intensity of drought in the rain-fed, maize-dominated, Midwestern US. Uncertainty in the availability of water, combined with an increased demand for non-grain ethanol feedstock, may necessitate expanding the production of more water-use-efficient and less drought sensitive crops for biomass applications. Research suggests that biomass sorghum [Sorghum bicolor (L.) Moench] is more drought tolerant and can produce more biomass than maize in water-limiting environments; however, sorghum water use data are limited for the rain-fed Midwestern US. To address this gap, a replicated (n=3) side-by-side trial was established in Ames, Iowa to determine cumulative water use and water-use-efficiency of maize and biomass sorghum. Data were collected by micrometeorological stations located in the center of each plot and used to calculate cumulative evapotranspiration throughout the 2014 growing season using the residual energy balance method. Continuous micrometeorological measurements were supplemented by periodic measurements of leaf area index (LAI) and above-ground biomass. At mid-point of the growing season, preliminary data analysis revealed similar water use for sorghum and maize. Data collection will continue for the remainder of the growing season, at which point a stronger conclusion can be drawn. This research will provide important insight on the potential hydrologic effects of expanding biomass sorghum production in the Midwestern, US.

  6. A modelling approach to evaluate the long-term effect of soil texture on spring wheat productivity under a rain-fed condition

    PubMed Central

    He, Yong; Hou, Lingling; Wang, Hong; Hu, Kelin; McConkey, Brian

    2014-01-01

    Soil surface texture is an important environmental factor that influences crop productivity because of its direct effect on soil water and complex interactions with other environmental factors. Using 30-year data, an agricultural system model (DSSAT-CERES-Wheat) was calibrated and validated. After validation, the modelled yield and water use (WU) of spring wheat (Triticum aestivum L.) from two soil textures (silt loam and clay) under rain-fed condition were analyzed. Regression analysis showed that wheat grown in silt loam soil is more sensitive to WU than wheat grown in clay soil, indicating that the wheat grown in clay soil has higher drought tolerance than that grown in silt loam. Yield variation can be explained by WU other than by precipitation use (PU). These results demonstrated that the DSSAT-CERES-Wheat model can be used to evaluate the WU of different soil textures and assess the feasibility of wheat production under various conditions. These outcomes can improve our understanding of the long-term effect of soil texture on spring wheat productivity in rain-fed condition. PMID:25074796

  7. Regulated expression of a cytokinin biosynthesis gene IPT delays leaf senescence and improves yield under rainfed and irrigated conditions in canola (Brassica napus L.).

    PubMed

    Kant, Surya; Burch, David; Badenhorst, Pieter; Palanisamy, Rajasekaran; Mason, John; Spangenberg, German

    2015-01-01

    Delay of leaf senescence through genetic modification can potentially improve crop yield, through maintenance of photosynthetically active leaves for a longer period. Plant growth hormones such as cytokinin regulate and delay leaf senescence. Here, the structural gene (IPT) encoding the cytokinin biosynthetic enzyme isopentenyltransferase was fused to a functionally active fragment of the AtMYB32 promoter and was transformed into canola plants. Expression of the AtMYB32xs::IPT gene cassette delayed the leaf senescence in transgenic plants grown under controlled environment conditions and field experiments conducted for a single season at two geographic locations. The transgenic canola plants retained higher chlorophyll levels for an extended period and produced significantly higher seed yield with similar growth and phenology compared to wild type and null control plants under rainfed and irrigated treatments. The yield increase in transgenic plants was in the range of 16% to 23% and 7% to 16% under rainfed and irrigated conditions, respectively, compared to control plants. Most of the seed quality parameters in transgenic plants were similar, and with elevated oleic acid content in all transgenic lines and higher oil content and lower glucosinolate content in one specific transgenic line as compared to control plants. The results suggest that by delaying leaf senescence using the AtMYB32xs::IPT technology, productivity in crop plants can be improved under water stress and well-watered conditions.

  8. Productivity and sustainability of rainfed wheat-soybean system in the North China Plain: results from a long-term experiment and crop modelling

    PubMed Central

    Qin, Wei; Wang, Daozhong; Guo, Xisheng; Yang, Taiming; Oenema, Oene

    2015-01-01

    A quantitative understanding of yield response to water and nutrients is key to improving the productivity and sustainability of rainfed cropping systems. Here, we quantified the effects of rainfall, fertilization (NPK) and soil organic amendments (with straw and manure) on yields of a rainfed wheat-soybean system in the North China Plain (NCP), using 30-years’ field experimental data (1982–2012) and the simulation model-AquaCrop. On average, wheat and soybean yields were 5 and 2.5 times higher in the fertilized treatments than in the unfertilized control (CK), respectively. Yields of fertilized treatments increased and yields of CK decreased over time. NPK + manure increased yields more than NPK alone or NPK + straw. The additional effect of manure is likely due to increased availability of K and micronutrients. Wheat yields were limited by rainfall and can be increased through soil mulching (15%) or irrigation (35%). In conclusion, combined applications of fertilizer NPK and manure were more effective in sustaining high crop yields than recommended fertilizer NPK applications. Manure applications led to strong accumulation of NPK and relatively low NPK use efficiencies. Water deficiency in wheat increased over time due to the steady increase in yields, suggesting that the need for soil mulching increases. PMID:26627707

  9. A modelling approach to evaluate the long-term effect of soil texture on spring wheat productivity under a rain-fed condition.

    PubMed

    He, Yong; Hou, Lingling; Wang, Hong; Hu, Kelin; McConkey, Brian

    2014-07-30

    Soil surface texture is an important environmental factor that influences crop productivity because of its direct effect on soil water and complex interactions with other environmental factors. Using 30-year data, an agricultural system model (DSSAT-CERES-Wheat) was calibrated and validated. After validation, the modelled yield and water use (WU) of spring wheat (Triticum aestivum L.) from two soil textures (silt loam and clay) under rain-fed condition were analyzed. Regression analysis showed that wheat grown in silt loam soil is more sensitive to WU than wheat grown in clay soil, indicating that the wheat grown in clay soil has higher drought tolerance than that grown in silt loam. Yield variation can be explained by WU other than by precipitation use (PU). These results demonstrated that the DSSAT-CERES-Wheat model can be used to evaluate the WU of different soil textures and assess the feasibility of wheat production under various conditions. These outcomes can improve our understanding of the long-term effect of soil texture on spring wheat productivity in rain-fed condition.

  10. Prevalence of Schistosoma japonicum infection of Oncomelania quadrasi snail colonies in 50 irrigated and rain-fed villages of Samar Province, the Philippines

    PubMed Central

    Madsen, Henry; Carabin, Hélène; Balolong, Don; Tallo, Veronica L; Olveda, Remigio; Yuan, M; McGarvey, Stephen T.

    2008-01-01

    A cross-sectional survey of Oncomelania quadrasi, the intermediate host for Schistosoma japonicum, was conducted between 2004 and 2005 in 50 villages of the Province of Samar, the Philippines. The villages were classified as rain-fed (25) or with some man-made irrigation system (25). The primary objective was to identify all snail colony sites in the 50 villages and to compare snail population density and S. japonicum infection prevalence between the two types of villages. The presence of snail colonies was surveyed along streams, springs, various canals and swampy areas or grass land. A total of 198 colony sites were identified out of the 845 sites surveyed. Of these, a sufficient number of O. quadrasi snails were identified to measure density and infection in 147 sites. Density of O. quadrasi was remarkably uniform across habitats and there were no significant differences across habitats and between village type. The prevalence of infected snails showed more variability among habitats. Indeed, there was an interaction between the type of habitat and the type of village with irrigated villages being associated with a prevalence proportion ratio of 5.76 (1.31, 25.42) as compared to rain-fed villages among streams and springs. No such association was found among other habitats. The results suggest that once a suitable habitat exists, O. quadrasi populations establish and reach a plateau density. These results are discussed in light of possible ecological measures of control. PMID:18207119

  11. Productivity and sustainability of rainfed wheat-soybean system in the North China Plain: results from a long-term experiment and crop modelling.

    PubMed

    Qin, Wei; Wang, Daozhong; Guo, Xisheng; Yang, Taiming; Oenema, Oene

    2015-12-02

    A quantitative understanding of yield response to water and nutrients is key to improving the productivity and sustainability of rainfed cropping systems. Here, we quantified the effects of rainfall, fertilization (NPK) and soil organic amendments (with straw and manure) on yields of a rainfed wheat-soybean system in the North China Plain (NCP), using 30-years' field experimental data (1982-2012) and the simulation model-AquaCrop. On average, wheat and soybean yields were 5 and 2.5 times higher in the fertilized treatments than in the unfertilized control (CK), respectively. Yields of fertilized treatments increased and yields of CK decreased over time. NPK + manure increased yields more than NPK alone or NPK + straw. The additional effect of manure is likely due to increased availability of K and micronutrients. Wheat yields were limited by rainfall and can be increased through soil mulching (15%) or irrigation (35%). In conclusion, combined applications of fertilizer NPK and manure were more effective in sustaining high crop yields than recommended fertilizer NPK applications. Manure applications led to strong accumulation of NPK and relatively low NPK use efficiencies. Water deficiency in wheat increased over time due to the steady increase in yields, suggesting that the need for soil mulching increases.

  12. Balanced N and C input recommendations for rain-fed maize production in northern China based on N balances and grain yields.

    PubMed

    Wang, Xiaobin; Cai, Dianxiong; Zhao, Quansheng; Xie, Xiaohong; Hoogmoed, Willem B; Oenema, Oene

    2017-07-07

    This study aimed to assess longer-term (1993-2009) effects of combined applications of fertiliser, maize stover, and cattle manure on maize yields, partial nitrogen (N) and carbon (C) balances, and water and N-use efficiencies, to guide N and C input recommendations for rain-fed maize production in northern China. The field trial, with three factors at five levels and 12 treatments, was conducted at Shouyang Dryland-Farming Experimental Station, Shanxi, China. Data analysis revealed higher N balances but lower C balances significantly occurred in a dry year than in a wet year. Positive N balances related to higher N inputs resulted in higher soil available N, even downward to deep layers with increasing N inputs, while positive C balances due to higher C inputs could be benefit to increase soil organic C. Based on partial N balances and grain yields, N and C inputs at ranges of 100 kg N ha(-1) and 1.9-2.9 Mg C ha(-1) could be recommended for target yields of 6.7-7.2 Mg ha(-1) in rain-fed maize production. The study suggests that N balances close to neutral be given priority to improving N-use efficiency, and more positive C balances also be important for sustaining target yields and soil fertility levels. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

  13. Phylogeography of Declining Relict and Lowland Leopard Frogs in the Desert Southwest of North America

    EPA Science Inventory

    We investigated the phylogeography of the closely related relict leopard frog (Rana onca) and lowland leopard frog (R. yavapaiensis) – two declining anurans from the warm-desert regions of southwestern North America. We used sequence data from two mitochondrial DNA genes to asses...

  14. Ecosystem and restoration consequences of invasive woody species removal in Hawaiian lowland wet forest

    Treesearch

    R. Ostertag; S. Cordell; J. Michaud; T.C. Cole; J.R. Schulten; K.M. Publico; J.H. Enoka

    2009-01-01

    A removal experiment was used to examine the restoration potential of a lowland wet forest in Hawaii, a remnant forest type that has been heavily invaded by non-native species and in which there is very little native species regeneration. All non-native woody and herbaceous biomass (approximately 45% of basal area) was removed in four 100-m² removal plots;...

  15. BIOGENIC VOLATILE ORGANIC COMPOUND EMISSIONS FROM A LOWLAND TROPICAL WET FOREST IN COSTA RICA

    EPA Science Inventory

    Twenty common plant species were screened for emissions of biogenic volatile organic compounds (BVOCS) at a lowland tropical wet forest site in Costa Rica. Ten of the species. examined emitted substantial quantities of isoprene. These species accounted for 35-50% of the total bas...

  16. Tephra layers as correlation tools of neogene coal-bearing strata from the Kenai lowland, Alaska

    SciTech Connect

    Reinink-Smith, L.M.

    1995-03-01

    Thirty-two tephra layers, exposed in coal beds of the Miocene and Pliocene Beluga and Sterling Formations along the shores of the Kenai lowland on the northwestern Kenai Peninsula, Alaska, were studied in detail to improve the geochronology and regional correlation of the Sterling Formation and test prior correlations that were based on palynology and physical tracing of beds over short distances. Published radiogenic isotope data suggest an age span of approximately 4 m.y. for the Sterling Formation at this location but give discordant ages for individual samples depending on dating techniques. A crystal-rich tephra layer near the middle of the section was traced across the Kenai lowland as one or two ash falls based on stratigraphic position, inertinite contents of adjacent coal, geochemical and mineralogical analyses, and individual characteristics. A pumice-rich layer deposited near the top of the Sterling Formation is preserved at two localities on the northwestern and southeastern sides of the Kenai lowland. Geochemical similarities, similar glass morphologies, and an absence of opaque phases characterize this layer as a single ash fall and allow correlation. On a regional scale, these correlations concur with previous correlations and show that a shallow anticline with a northwest-southeast-trending axis extends across the Kenai lowland. 28 refs., 14 figs., 1 tab.

  17. Widespread loess-like deposit in the Martian northern lowlands identifies Middle Amazonian climate change

    USGS Publications Warehouse

    Skinner, James A.; Tanaka, Kenneth L.; Thomas Platz,

    2014-01-01

    Consistently mappable units critical to distinguishing the style and interplay of geologic processes through time are sparse in the Martian lowlands. This study identifies a previously unmapped Middle Amazonian (ca. 1 Ga) unit (Middle Amazonian lowland unit, mAl) that postdates the Late Hesperian and Early Amazonian lowland plains by >2 b.y. The unit is regionally defined by subtle marginal scarps and slopes, has a mean thickness of 32 m, and extends >3.1 × 106 km2 between lat 35°N and 80°N. Pedestal-type craterforms and nested, arcuate ridges (thumbprint terrain) tend to occur adjacent to unit mAl outcrops, suggesting that current outcrops are vestiges of a more extensive deposit that previously covered ∼16 × 106 km2. Exposed layers, surface pits, and the draping of subjacent landforms allude to a sedimentary origin, perhaps as a loess-like deposit emplaced rhythmically through atmospheric fallout. We propose that unit mAl accumulated coevally with, and at the expense of, the erosion of the north polar basal units, identifying a major episode of Middle Amazonian climate-driven sedimentation in the lowlands. This work links ancient sedimentary processes to climate change that occurred well before those implied by current orbital and spin axis models.

  18. Andean Mountain Building Did not Preclude Dispersal of Lowland Epiphytic Orchids in the Neotropics.

    PubMed

    Pérez-Escobar, Oscar Alejandro; Gottschling, Marc; Chomicki, Guillaume; Condamine, Fabien L; Klitgård, Bente B; Pansarin, Emerson; Gerlach, Günter

    2017-07-07

    The Andean uplift is one of the major orographic events in the New World and has impacted considerably the diversification of numerous Neotropical lineages. Despite its importance for biogeography, the specific role of mountain ranges as a dispersal barrier between South and Central American lowland plant lineages is still poorly understood. The swan orchids (Cycnoches) comprise ca 34 epiphytic species distributed in lowland and pre-montane forests of Central and South America. Here, we study the historical biogeography of Cycnoches to better understand the impact of the Andean uplift on the diversification of Neotropical lowland plant lineages. Using novel molecular sequences (five nuclear and plastid regions) and twelve biogeographic models, we infer that the most recent common ancestor of Cycnoches originated in Amazonia ca 5 Mya. The first colonization of Central America occurred from a direct migration event from Amazonia, and multiple bidirectional trans-Andean migrations between Amazonia and Central America took place subsequently. Notably, these rare biological exchanges occurred well after major mountain building periods. The Andes have limited plant migration, yet it has seldom allowed episodic gene exchange of lowland epiphyte lineages such as orchids with great potential for effortless dispersal because of the very light, anemochorous seeds.

  19. The Land Remembers: Landscape Terms and Place Names in Lowland Chontal of Oaxaca, Mexico

    ERIC Educational Resources Information Center

    O'Connor, Loretta; Kroefges, Peter C.

    2008-01-01

    This paper examines landscape terminology and place names of the Chontal region in the state of Oaxaca in southern Mexico, with a focus on terms from Lowland Chontal, a highly endangered language spoken near the Pacific coast. In addition to the linguistic analysis, the paper presents a general description of the physical geography of the area and…

  20. Seasonal rainfall-runoff relationships in a lowland forested watershed in the southeastern USA

    Treesearch

    Ileana La Torre Torres; Devendra Amatya; Ge Sun; Timothy Callahan

    2011-01-01

    Hydrological processes of lowland watersheds of the southern USA are not well understood compared to a hilly landscape due to their unique topography, soil compositions, and climate. This study describes the seasonal relationships between rainfall patterns and runoff (sum of storm flow and base flow) using 13 years (1964–1976) of rainfall and stream flow data for a low...

  1. Evaluating barriers to native seedling establishment in an invaded Hawaiian lowland wet forest

    Treesearch

    S. Cordell; R. Ostertag; B. Rowe; L. Sweinhart; L. Vasquez-Radonic; J. Michaud; T.C. Cole; J.R. Schulten

    2009-01-01

    Many tropical island forest ecosystems are dominated by non-native plant species and lack native species regeneration in the understorey. Comparison of replicated control and removal plots offers an opportunity to examine not only invasive species impacts but also the restoration potential of native species. In lowland Hawaiian wet forests little is known about native...

  2. Phylogeography of Declining Relict and Lowland Leopard Frogs in the Desert Southwest of North America

    EPA Science Inventory

    We investigated the phylogeography of the closely related relict leopard frog (Rana onca) and lowland leopard frog (R. yavapaiensis) – two declining anurans from the warm-desert regions of southwestern North America. We used sequence data from two mitochondrial DNA genes to asses...

  3. Suspected macular degeneration in a captive Western lowland gorilla (Gorilla gorilla gorilla).

    PubMed

    Steinmetz, Andrea; Bernhard, Andreas; Sahr, Sabine; Oechtering, Gerhard

    2012-09-01

    The case of a 31-year-old captive female Western lowland gorilla (Gorilla gorilla gorilla) with decreased near vision but good distance vision is presented. Examination of the fundus revealed drusen-like bodies in the macula presumably because of an age-related macular degeneration (AMD). © 2012 American College of Veterinary Ophthalmologists.

  4. Malignant hypertension and retinopathy in a western lowland gorilla (Gorilla gorilla gorilla).

    PubMed

    Niemuth, Jennifer N; De Voe, Ryan S; Jennings, Samuel H; Loomis, Michael R; Troan, Brigid V

    2014-08-01

    A 34-year-old western lowland gorilla presented with peracute blindness. Clinical evaluation, diagnostic imaging, laboratory analyses, blood pressure measurements, and necropsy were performed. The clinical and postmortem findings supported malignant hypertension. We describe a case of naturally occurring hypertensive encephalopathy and retinopathy in a gorilla. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  5. Patterns of primary succession of native and introduced plants in lowland wet forests in eastern Hawaii

    Treesearch

    Naupaka Zimmerman; Flint 1 Hughes; Patrick Hart; Heather Kalei Chang; David Perez; Ryan Kaipoalohaakala Like; Rebecca. Ostertag

    2008-01-01

    The majority of Hawaii's lowland wet forests no longer exist, with many of the last remaining patches found on the eastern, windward sides of the largest islands. To better understand successional patterns and invasion in these native systems, we quantified basal area (BA) and densities of woody species and understory cover at nine sites in the Puna district on...

  6. The Land Remembers: Landscape Terms and Place Names in Lowland Chontal of Oaxaca, Mexico

    ERIC Educational Resources Information Center

    O'Connor, Loretta; Kroefges, Peter C.

    2008-01-01

    This paper examines landscape terminology and place names of the Chontal region in the state of Oaxaca in southern Mexico, with a focus on terms from Lowland Chontal, a highly endangered language spoken near the Pacific coast. In addition to the linguistic analysis, the paper presents a general description of the physical geography of the area and…

  7. An analysis of modern pollen rain from the Maya lowlands of northern Belize

    USGS Publications Warehouse

    Bhattacharya, T.; Beach, T.; Wahl, D.

    2011-01-01

    In the lowland Maya area, pollen records provide important insights into the impact of past human populations and climate change on tropical ecosystems. Despite a long history of regional paleoecological research, few studies have characterized the palynological signatures of lowland ecosystems, a fact which lowers confidence in ecological inferences made from palynological data. We sought to verify whether we could use pollen spectra to reliably distinguish modern ecosystem types in the Maya lowlands of Central America. We collected 23 soil and sediment samples from eight ecosystem types, including upland, riparian, secondary, and swamp (bajo) forests; pine savanna; and three distinct wetland communities. We analyzed pollen spectra with non-metric multidimensional scaling (NMDS), and found significant compositional differences in ecosystem types' pollen spectra. Forested sites had spectra dominated by Moraceae/Urticaceae pollen, while non-forested sites had significant portions of Poaceae, Asteraceae, and Amaranthaceae pollen. Upland, bajo, and riparian forest differed in representation of Cyperaceae, Bactris-type, and Combretaceae/Melastomataceae pollen. High percentages of pine (Pinus), oak (Quercus), and the presence of Byrsonima characterized pine savanna. Despite its limited sample size, this study provides one of the first statistical analyses of modern pollen rain in the Maya lowlands. Our results show that pollen assemblages can accurately reflect differences between ecosystem types, which may help refine interpretations of pollen records from the Maya area. ?? 2010 Elsevier B.V.

  8. Alien Roadside Species More Easily Invade Alpine than Lowland Plant Communities in a Subarctic Mountain Ecosystem

    PubMed Central

    Lembrechts, Jonas J.; Milbau, Ann; Nijs, Ivan

    2014-01-01

    Effects of roads on plant communities are not well known in cold-climate mountain ecosystems, where road building and development are expected to increase in future decades. Knowledge of the sensitivity of mountain plant communities to disturbance by roads is however important for future conservation purposes. We investigate the effects of roads on species richness and composition, including the plant strategies that are most affected, along three elevational gradients in a subarctic mountain ecosystem. We also examine whether mountain roads promote the introduction and invasion of alien plant species from the lowlands to the alpine zone. Observations of plant community composition were made together with abiotic, biotic and anthropogenic factors in 60 T-shaped transects. Alpine plant communities reacted differently to road disturbances than their lowland counterparts. On high elevations, the roadside species composition was more similar to that of the local natural communities. Less competitive and ruderal species were present at high compared with lower elevation roadsides. While the effects of roads thus seem to be mitigated in the alpine environment for plant species in general, mountain plant communities are more invasible than lowland communities. More precisely, relatively more alien species present in the roadside were found to invade into the surrounding natural community at high compared to low elevations. We conclude that effects of roads and introduction of alien species in lowlands cannot simply be extrapolated to the alpine and subarctic environment. PMID:24586947

  9. Accumulation of metallic elements by Amanita muscaria from rural lowland and industrial upland regions.

    PubMed

    Lipka, Krzysztof; Falandysz, Jerzy

    2017-03-04

    This study was carried out on the accumulation and occurrence of Ag, Al, Ba, Ca, Cd, Co, Cu, Fe, Hg, K, Mg, Mn, Na, Rb, Sr and Zn in the mushroom Amanita muscaria and forest topsoil from two lowland sites in the Tuchola Pinewoods in the north-central region and an upland site in the Świetokrzyskie Mountains in the south-central region of Poland. Topsoil from the upland location showed Ag, Al, Ba, Ca, Cd, Co, Cu, Fe, Hg, Na and Zn at significantly higher concentration levels (pseudo-total fraction and often also the labile or extractable fraction) than at both lowland locations, where topsoil was richer in Mg, and similar in Rb. Amanita muscaria from the upland region differed from individuals collected in the lowland sites by higher concentration levels of Cd, Cu, Hg and Mn in caps. This could be related to higher concentration levels of the metallic elements in topsoil in the upland region. On other side, A. muscaria from the upland site was poorer in Co and Fe in caps, and in Ca, Co, Fe and Sr in stipes. In spite of the differences in content of the geogenic metallic elements in topsoil between the lowland and upland locations, A. muscaria from both regions was able to regulate uptake and accumulation of Ag, Al, Ba, Ca, K, Mg, Na, Rb and Zn, which were at similar concentration levels in caps but not necessarily in stipes.

  10. Dental Screening and Education Among Cambodian, Lowland Lao, and Hmong Refugees in Fresno County, California.

    ERIC Educational Resources Information Center

    Rowe, Donald R.; Jackson, Sidney

    1988-01-01

    Ascertains the dental health needs of the following refugee groups in Fresno County, California: (1) Cambodians; (2) lowland Lao; and (3) Hmong. Discusses successful health marketing and educational strategies aimed at these groups. A Dental Screening program instructed community health specialists, provided dental health education, and performed…

  11. Instream wood as a driver of nutrient attenuation in a lowland sandy stream

    NASA Astrophysics Data System (ADS)

    Klaar, Megan; Shelley, Felicity; Blaen, Phil; Dapelo, Davide; Trimmer, Mark; Bridgeman, John; Hannah, David; Krause, Stefan

    2016-04-01

    Our poster outlines our research to assess the potential of instream wood to enhance nutrient (nitrogen and carbon) attenuating potential in UK lowland rivers. Using cutting-edge distributed temperature sensing, geophysical technologies, novel microbial metabolic activity tracers and 15N isotope tracer applications, we are able to identify how instream wood alters hyporheic exchange fluxes and residence times which control the development and occurrence of biogeochemical hotspots, which facilitate nitrogen removal. Initial results show that instream wood increases surface water downwelling into the hyporheic, creating increased hyporheic mixing. Metabolic tracer, nutrient and modelling data reveal a correlation between these hyporheic exchange flow locations and increased denitrification hotspots. This data in conjunction with ongoing experimentation suggests that instream wood could be used in river basin management and river restoration efforts to improve water quality and hydromorphic integrity within lowland sandy streams. Ongoing work seeks to quantify the efficiency of alternative (stationary and transient) wood designs for controlled alteration and management of hyporheic exchange fluxes and residence times and nutrient turnover in the streambed. Outputs from this project will provide a quantitative understanding of the optimal design and efficiency of instream wood structures for removing excess nitrate from streambed sediments of nutrient impacted lowland rivers. This information will directly impact UK and European river restoration policies and inform decisions of whether wood restoration in UK lowland rivers should be promoted on a national level and how the most efficient strategies should be designed.

  12. Cross-Sectional Comparison of Sleep-Disordered Breathing in Native Peruvian Highlanders and Lowlanders.

    PubMed

    Pham, Luu V; Meinzen, Christopher; Arias, Rafael S; Schwartz, Noah G; Rattner, Adi; Miele, Catherine H; Smith, Philip L; Schneider, Hartmut; Miranda, J Jaime; Gilman, Robert H; Polotsky, Vsevolod Y; Checkley, William; Schwartz, Alan R

    2017-03-01

    Pham, Luu V., Christopher Meinzen, Rafael S. Arias, Noah G. Schwartz, Adi Rattner, Catherine H. Miele, Philip L. Smith, Hartmut Schneider, J. Jaime Miranda, Robert H. Gilman, Vsevolod Y. Polotsky, William Checkley, and Alan R. Schwartz. Cross-sectional comparison of sleep-disordered breathing in native Peruvian highlanders and lowlanders. High Alt Med Biol. 18:11-19, 2017.

  13. BIOGENIC VOLATILE ORGANIC COMPOUND EMISSIONS FROM A LOWLAND TROPICAL WET FOREST IN COSTA RICA

    EPA Science Inventory

    Twenty common plant species were screened for emissions of biogenic volatile organic compounds (BVOCS) at a lowland tropical wet forest site in Costa Rica. Ten of the species. examined emitted substantial quantities of isoprene. These species accounted for 35-50% of the total bas...

  14. Approaches to restoration of oak forests on farmed lowlands of the Mississippi River and its tributaries

    Treesearch

    Emile S. Gardiner; Daniel C. Dey; John A. Stanturf; Brian Roy. Lockhart

    2010-01-01

    The lowlands associated with the Mississippi River and its tributaries historically supported extensive broadleaf forests that were particularly rich in oak (Quercus spp.) species. Beginning in the 1700s, deforestation for agriculture substantially reduced the extent of the original forest, and fragmented the remainder into small parcels. More...

  15. Plant available silicon in South-east Asian rice paddy soils - relevance of agricultural practice and of abiotic factors

    NASA Astrophysics Data System (ADS)

    Marxen, A.; Klotzbücher, T.; Vetterlein, D.; Jahn, R.

    2012-12-01

    Background Silicon (Si) plays a crucial role in rice production. Si content of rice plants exceeds the content of other major nutrients such as nitrogen, phosphorous or potassium. Recent studies showed that in some environments external supply of Si can enhance the growth of rice plants. Rice plants express specific Si transporters to absorb Si from soil solutions in form of silicic acid, which precipitates in tissue cells forming amorphous silica bodies, called phytoliths. The phytoliths are returned to soils with plant residues. They might be a main source of plant available silicic acid in soils. Aims In this study we assess the effects of rice paddy cultivation on the stocks of `reactive` Si fractions in mineral topsoils of rice paddy fields in contrasting landscapes. The `reactive` Si fractions are presumed to determine the release of plant-available silicic acid in soils. We consider the relevance of abiotic factors (mineral assemblage; soil weathering status) and agricultural practice for these fractions. Agricultural practices, which were assumed to affect the stocks of `reactive` Si were (i) the usage of different rice varieties (which might differ in Si demand), (ii) straw residue management (i.e., whether straw residues are returned to the fields or removed and used e.g. as fodder), and (iii) yield level and number of crops per year. Material and methods Soils (top horizon of about 0-20 cm depth) were sampled from rice paddy fields in 2 mountainous and 5 lowland landscapes of contrasting geologic conditions in Vietnam and the Philippines. Ten paddy fields were sampled per landscape. The rice paddy management within landscapes differed when different farmers and/or communities managed the fields. We analysed the following fractions of `reactive` Si in the soils: acetate-extractable Si (dissolved and easily exchangeable Si), phosphate-extractable Si (adsorbed Si), oxalate extractable Si (Si associated with poorly-ordered sesquioxides), NaOH extractable Si

  16. Rice-Map: a new-generation rice genome browser

    PubMed Central

    2011-01-01

    Background The concurrent release of rice genome sequences for two subspecies (Oryza sativa L. ssp. japonica and Oryza sativa L. ssp. indica) facilitates rice studies at the whole genome level. Since the advent of high-throughput analysis, huge amounts of functional genomics data have been delivered rapidly, making an integrated online genome browser indispensable for scientists to visualize and analyze these data. Based on next-generation web technologies and high-throughput experimental data, we have developed Rice-Map, a novel genome browser for researchers to navigate, analyze and annotate rice genome interactively. Description More than one hundred annotation tracks (81 for japonica and 82 for indica) have been compiled and loaded into Rice-Map. These pre-computed annotations cover gene models, transcript evidences, expression profiling, epigenetic modifications, inter-species and intra-species homologies, genetic markers and other genomic features. In addition to these pre-computed tracks, registered users can interactively add comments and research notes to Rice-Map as User-Defined Annotation entries. By smoothly scrolling, dragging and zooming, users can browse various genomic features simultaneously at multiple scales. On-the-fly analysis for selected entries could be performed through dedicated bioinformatic analysis platforms such as WebLab and Galaxy. Furthermore, a BioMart-powered data warehouse "Rice Mart" is offered for advanced users to fetch bulk datasets based on complex criteria. Conclusions Rice-Map delivers abundant up-to-date japonica and indica annotations, providing a valuable resource for both computational and bench biologists. Rice-Map is publicly accessible at http://www.ricemap.org/, with all data available for free downloading. PMID:21450055

  17. The Submergence Tolerance Regulator SUB1A Mediates Crosstalk between Submergence and Drought Tolerance in Rice[W][OA

    PubMed Central

    Fukao, Takeshi; Yeung, Elaine; Bailey-Serres, Julia

    2011-01-01

    Submergence and drought are major constraints to rice (Oryza sativa) production in rain-fed farmlands, both of which can occur sequentially during a single crop cycle. SUB1A, an ERF transcription factor found in limited rice accessions, dampens ethylene production and gibberellic acid responsiveness during submergence, economizing carbohydrate reserves and significantly prolonging endurance. Here, we evaluated the functional role of SUB1A in acclimation to dehydration. Comparative analysis of genotypes with and without SUB1A revealed that SUB1A enhanced recovery from drought at the vegetative stage through reduction of leaf water loss and lipid peroxidation and increased expression of genes associated with acclimation to dehydration. Overexpression of SUB1A augmented ABA responsiveness, thereby activating stress-inducible gene expression. Paradoxically, vegetative tissue undergoes dehydration upon desubmergence even though the soil contains sufficient water, indicating that leaf desiccation occurs in the natural progression of a flooding event. Desubmergence caused the upregulation of gene transcripts associated with acclimation to dehydration, with higher induction in SUB1A genotypes. SUB1A also restrained accumulation of reactive oxygen species (ROS) in aerial tissue during drought and desubmergence. Consistently, SUB1A increased the abundance of transcripts encoding ROS scavenging enzymes, resulting in enhanced tolerance to oxidative stress. Therefore, in addition to providing robust submergence tolerance, SUB1A improves survival of rapid dehydration following desubmergence and water deficit during drought. PMID:21239643

  18. Controls on anastomosis in lowland river systems: Towards process-based solutions to habitat conservation.

    PubMed

    Marcinkowski, Paweł; Grabowski, Robert C; Okruszko, Tomasz

    2017-12-31

    Anastomosing rivers were historically common around the world before extensive agricultural and industrial development in river valleys. Few lowland anastomosing rivers remain in temperate zones, and the protection of these river-floodplain systems is an international conservation priority. However, the mechanisms that drive the creation and maintenance of multiple channels, i.e. anabranches, are not well understood, particularly for lowland rivers, making it challenging to identify effective management strategies. This study uses a novel multi-scale, process-based hydro-geomorphological approach to investigate the natural and anthropogenic controls on anastomosis in lowland river reaches. Using a wide range of data (hydrologic, cartographic, remote-sensing, historical), the study (i) quantifies changes in the planform of the River Narew, Poland over the last 100years, (ii) documents changes in the natural and anthropogenic factors that could be driving the geomorphic change, and (iii) develops a conceptual model of the controls of anastomosis. The results show that 110km of anabranches have been lost from the Narew National Park (6810ha), a 42% reduction in total anabranch length since 1900. The rates of anabranch loss have increased as the number of pressures inhibiting anabranch creation and maintenance has multiplied. The cessation of localized water level and channel management (fishing dams, water mills and timber rafting), the loss of traditional floodplain activities (seasonal mowing) and infrastructure construction (embanked roads and an upstream dam) are contributing to low water levels and flows, the deposition of sediment at anabranch inlets, the encroachment of common reed (Phragmites australis), and the eventual loss of anabranches. By identifying the processes driving the loss of anabranches, this study provides transferable insights into the controls of anastomosis in lowland rivers and the management solutions needed to preserve the unique

  19. Functional trait composition of aquatic plants can serve to disentangle multiple interacting stressors in lowland streams.

    PubMed

    Baattrup-Pedersen, Annette; Göthe, Emma; Riis, Tenna; O'Hare, Matthew T

    2016-02-01

    Historically, close attention has been paid to negative impacts associated with nutrient loads to streams and rivers, but today hydromorphological alterations are considered increasingly implicated when lowland streams do not achieve good ecological status. Here, we explore if trait-abundance patterns of aquatic plants change along gradients in hydromorphological degradation and eutrophication in lowland stream sites located in Denmark. Specifically, we hypothesised that: i) changes in trait-abundance patterns occur along gradients in hydromorphological degradation and ii) trait-abundance patterns can serve to disentangle effects of eutrophication and hydromorphological degradation in lowland streams reflecting that the mechanisms behind changes differ. We used monitoring data from a total of 147 stream reaches with combined data on aquatic plant species abundance, catchment land use, hydromorphological alterations (i.e. planform, cross section, weed cutting) and water chemistry parameters. Traits related to life form, dispersal, reproduction and survival together with ecological preference values for nutrients and light (Ellenberg N and L) were allocated to 41 species representing 79% of the total species pool. We found clear evidence that habitat degradation (hydromorphological alterations and eutrophication) mediated selective changes in the trait-abundance patterns of the plant community. Specific traits could distinguish hydromorphological degradation (free-floating, surface; anchored floating leaves; anchored heterophylly) from eutrophication (free-floating, submerged; leaf area). We provide a conceptual framework for interpretation of how eutrophication and hydromorphological degradation interact and how this is reflected in trait-abundance patterns in aquatic plant communities in lowland streams. Our findings support the merit of trait-based approaches in biomonitoring as they shed light on mechanisms controlling structural changes under environmental

  20. Can lowland dry forests represent a refuge from avian malaria for native Hawaiian birds?

    USGS Publications Warehouse

    Tucker-Mohl, Katherine; Hart, Patrick; Atkinson, Carter T.

    2010-01-01

    Hawaii's native birds have become increasingly threatened over the past century. Introduced mosquito borne diseases such as avian malaria may be responsible for the near absence of endemic Hawaiian forest birds in low-elevation habitats. The recent recognition that some native Hawaiian forest birds may be repopulating moist lowland habitats as a result of evolved resistance to this disease has increased the conservation value of these areas. Here, we investigate whether remnant low elevation dry forests on Hawaii Island provide natural 'refuges' from mosquito-transmitted malaria by nature of their low rainfall and absence of suitable natural sources of water for mosquito breeding. Unlike lowland wet forests where high rates of disease transmission may be selecting for disease resistance, lowland dry forests may provide some refuge for native forest birds without natural resistance to malaria. We mistnetted forest birds in two lowland dry forests and tested all native birds by microscopy and serology for avian malaria caused by the Plasmodium relictum parasite. We also conducted surveys for standing water and mosquito larvae. Overall prevalence of infections with Plasmodium relictum in the Hawaii Amakihi Hemignathus virens virens was 15%. Most infected birds had lowlevel parasitemias, suggesting chronic infections. Although avian malaria is present in these lowland dry forest Amakihi populations, infection rates are significantly lower than in wet forest populations at similar elevations. Sources of breeding mosquitoes in these forests appeared to be largely anthropogenic; thus, there is potential to manage dry forests as mosquito-free habitat for Hawaii Amakihi and other Hawaiian forest birds.

  1. Lowland tapir (Tapirus terrestris) distribution, activity patterns and relative abundance in the Greater Madidi-Tambopata Landscape.

    PubMed

    Wallace, Robert; Ayala, Guido; Viscarra, Maria

    2012-12-01

    Lowland tapir distribution is described in northwestern Bolivia and southeastern Peru within the Greater Madidi-Tambopata Landscape, a priority Tapir Conservation Unit, using 1255 distribution points derived from camera trapping efforts, field research and interviews with park guards from 5 national protected areas and hunters from 19 local communities. A total of 392 independent camera trapping events from 14 camera trap surveys at 11 sites demonstrated the nocturnal and crepuscular activity patterns (86%) of the lowland tapir and provide 3 indices of relative abundance for spatial and temporal comparison. Capture rates for lowland tapirs were not significantly different between camera trapping stations placed on river beaches versus those placed in the forest. Lowland tapir capture rates were significantly higher in the national protected areas of the region versus indigenous territories and unprotected portions of the landscape. Capture rates through time suggested that lowland tapir populations are recovering within the Tuichi Valley, an area currently dedicated towards ecotourism activities, following the creation (1995) and subsequent implementation (1997) of the Madidi National Park in Bolivia. Based on our distributional data and published conservative estimates of population density, we calculated that this transboundary landscape holds an overall lowland tapir population of between 14 540 and 36 351 individuals, of which at least 24.3% are under protection from national and municipal parks. As such, the Greater Madidi-Tambopata Landscape should be considered a lowland tapir population stronghold and priority conservation efforts are discussed in order to maintain this population.

  2. Genotypic and phenotypic characterization of genetic differentiation and diversity in the USDA rice mini-core collection.

    PubMed

    Li, Xiaobai; Yan, Wengui; Agrama, Hesham; Hu, Biaolin; Jia, Limeng; Jia, Melissa; Jackson, Aaron; Moldenhauer, Karen; McClung, Anna; Wu, Dianxing

    2010-12-01

    A rice mini-core collection consisting of 217 accessions has been developed to represent the USDA core and whole collections that include 1,794 and 18,709 accessions, respectively. To improve the efficiency of mining valuable genes and broadening the genetic diversity in breeding, genetic structure and diversity were analyzed using both genotypic (128 molecular markers) and phenotypic (14 numerical traits) data. This mini-core had 13.5 alleles per locus, which is the most among the reported germplasm collections of rice. Similarly, polymorphic information content (PIC) value was 0.71 in the mini-core which is the highest with one exception. The high genetic diversity in the mini-core suggests there is a good possibility of mining genes of interest and selecting parents which will improve food production and quality. A model-based clustering analysis resulted in lowland rice including three groups, aus (39 accessions), indica (71) and their admixtures (5), upland rice including temperate japonica (32), tropical japonica (40), aromatic (6) and their admixtures (12) and wild rice (12) including glaberrima and four other species of Oryza. Group differentiation was analyzed using both genotypic distance Fst from 128 molecular markers and phenotypic (Mahalanobis) distance D(2) from 14 traits. Both dendrograms built by Fst and D(2) reached similar-differentiative relationship among these genetic groups, and the correlation coefficient showed high value 0.85 between Fst matrix and D(2) matrix. The information of genetic and phenotypic differentiation could be helpful for the association mapping of genes of interest. Analysis of genotypic and phenotypic diversity based on genetic structure would facilitate parent selection for broadening genetic base of modern rice cultivars via breeding effort.

  3. Selenate-enriched urea granules are a highly effective fertilizer for selenium biofortification of paddy rice grain.

    PubMed

    Premarathna, Lakmalie; McLaughlin, Mike J; Kirby, Jason K; Hettiarachchi, Ganga M; Stacey, Samuel; Chittleborough, David J

    2012-06-13

    This study examined the effects of applied selenium (Se) species, time of application, method of application, and soil water management regimen on the accumulation of Se in rice plants. Plants were grown to maturity in a temperature- and humidity-controlled growth chamber using three water management methods: field capacity (FC), submerged until harvest, and submerged and drained 2 weeks before harvest. Two Se species, selenate (SeO4(2-)) and selenite (SeO3(2-)), were applied at a rate equivalent to 30 g ha(-1). Four application methods were employed as follows: (i) Se applied at soil preparation, (ii) Se-enriched urea granules applied to floodwater at heading; (iii) foliar Se applied at heading; and (iv) fluid fertilizer Se applied to soil or floodwater at heading. Total Se concentrations in rice grains, husks, leaves, culms, and roots were measured, as well as Se speciation in grains from the Se-enriched urea granule treatment. Highest Se concentrations in the grain occurred with SeO4(2-) and with fertilizer applied at heading stage; SeO4(2-)-enriched urea granules applied at heading increased grain Se concentrations 5-6-fold (by 450-600 μg kg(-1)) compared to the control (no fertilizer Se applied) in all water treatments. Under paddy conditions other Se fertilization strategies were much less effective. Drainage before harvesting caused Se to accumulate in/on rice roots, possibly through adsorption onto iron plaque on roots. Rice grains contained Se mainly in the organic form as selenomethionine (SeM), which comprised >90% of the total grain Se in treatments fertilized with SeO4(2-)-enriched urea granules. The results of this study clearly show that of the fertilizer strategies tested biofortification of Se in rice grains can best be achieved in lowland rice by broadcast application of SeO4(2-)-enriched urea granules to floodwater at heading stage.

  4. Greenhouse gas emissions and global warming potential of traditional and diversified tropical rice rotation systems.

    PubMed

    Weller, Sebastian; Janz, Baldur; Jörg, Lena; Kraus, David; Racela, Heathcliff S U; Wassmann, Reiner; Butterbach-Bahl, Klaus; Kiese, Ralf

    2016-01-01

    Global rice agriculture will be increasingly challenged by water scarcity, while at the same time changes in demand (e.g. changes in diets or increasing demand for biofuels) will feed back on agricultural practices. These factors are changing traditional cropping patterns from double-rice cropping to the introduction of upland crops in the dry season. For a comprehensive assessment of greenhouse gas (GHG) balances, we measured methane (CH4 )/nitrous oxide (N2 O) emissions and agronomic parameters over 2.5 years in double-rice cropping (R-R) and paddy rice rotations diversified with either maize (R-M) or aerobic rice (R-A) in upland cultivation. Introduction of upland crops in the dry season reduced irrigation water use and CH4 emissions by 66-81% and 95-99%, respectively. Moreover, for practices including upland crops, CH4 emissions in the subsequent wet season with paddy rice were reduced by 54-60%. Although annual N2 O emissions increased two- to threefold in the diversified systems, the strong reduction in CH4 led to a significantly lower (P < 0.05) annual GWP (CH4  + N2 O) as compared to the traditional double-rice cropping system. Measurements of soil organic carbon (SOC) contents before and 3 years after the introduction of upland crop rotations indicated a SOC loss for the R-M system, while for the other systems SOC stocks were unaffected. This trend for R-M systems needs to be followed as it has significant consequences not only for the GWP balance but also with regard to soil fertility. Economic assessment showed a similar gross profit span for R-M and R-R, while gross profits for R-A were reduced as a consequence of lower productivity. Nevertheless, regarding a future increase in water scarcity, it can be expected that mixed lowland-upland systems will expand in SE Asia as water requirements were cut by more than half in both rotation systems with upland crops. © 2015 John Wiley & Sons Ltd.

  5. Net global warming potential and greenhouse gas intensity of conventional and conservation agriculture system in rainfed semi arid tropics of India

    NASA Astrophysics Data System (ADS)

    Pratibha, G.; Srinivas, I.; Rao, K. V.; Shanker, Arun K.; Raju, B. M. K.; Choudhary, Deepak K.; Srinivas Rao, K.; Srinivasarao, Ch.; Maheswari, M.

    2016-11-01

    Agriculture has been considered as one of the contributors to greenhouse gas (GHG) emissions and it continues to increase with increase in crop production. Hence development of sustainable agro techniques with maximum crop production, and low global warming potential is need of the hour. Quantifying net global warming potential (NGWP) and greenhouse gas intensity (GHGI) of an agricultural activity is a method to assess the mitigation potential of the activity. But there is dearth of information on NGWP of conservation agriculture under rainfed conditions. Hence in this study two methods such as crop based (NGWPcrop) and soil based (NGWPsoil) were estimated from the data of the experiment initiated in 2009 in rainfed semiarid regions of Hyderabad, India with different tillage practices like conventional tillage (CT), reduced tillage (RT), zero tillage (ZT) and residue retention levels by harvesting at different heights which includes 0, 10 and 30 cm anchored residue in pigeonpea-castor systems. The results of the study revealed that under rainfed conditions CT recorded 24% higher yields over ZT, but CT and RT were on par with each other. However, the yield gap between the tillage treatments is narrowing down over 5 years of study. ZT and RT recorded 26 and 11% lower indirect GHG emissions (emissions from farm operations and input use) over CT, respectively. The percent contribution of CO2 eq. N2O emission is higher to total GHG emissions in both the crops. Both NGWPcrop, NGWPsoil, GHGIcrop, and GHGIsoil based were influenced by tillage and residue treatments. Further, castor grown on pigeonpea residue recorded 20% higher GHG emissions over pigeonpea grown on castor residues. The fuel consumption in ZT was reduced by 58% and 81% as compared to CT in pigeonpea and castor, respectively. Lower NGWP and GHGI based on crop and soil was observed with increase in crop residues and decrease in tillage intensity in both the crops. The results of the study indicate that, there

  6. Soil Incorporation of Silica-Rich Rice Husk Decreases Inorganic Arsenic in Rice Grain.

    PubMed

    Seyfferth, Angelia L; Morris, Andrew H; Gill, Rattandeep; Kearns, Kelli A; Mann, Jessica N; Paukett, Michelle; Leskanic, Corey

    2016-05-18

    Arsenic decreases rice yield, and inorganic grain As threatens human health; thus, strategies to decrease rice As are critically needed. Increased plant-available silica (Si) can decrease rice As, yet the source of Si matters. Rice husk, an underutilized and Si-rich byproduct of rice production that contains less labile C and an order of magnitude less As than rice straw, may be an economically viable Si resource to decrease rice As, yet the impact of rice husk incorporation on As in the rice-soil nexus has not been reported. This proof-of-concept study shows that rice husk incorporation to soil (1% w/w) decreases inorganic grain As by 25-50% without negatively affecting grain Cd, yield, or dissolved CH4 levels. Rice husk is a critical yet perhaps overlooked resource to improve soil quality through enhanced nutrient availability and attenuate human health risks through consumption of As-laden grain.

  7. Rice in an interdependent world.

    PubMed

    Falck, V T

    1991-01-01

    The purpose of this paper is to examine the outcome of the increasing need and dependence on rice as an essential food, and the potential hazards of this trajectory in an interdependent world, and to propose the need for a supranational system to guide decisions made in areas of mutual dependency among nations. All rice producing countries of the world should be responsible for assuring sufficient quantities and qualities of rice for the world's population. However, there are hazards related to emphasis on rice yields associated with the neglect of overall nutritional needs and also the potential for environmental impact given the need for sustainable development. Scientific measurement and data analyses of interdependent supranational variables are needed to guide policies and practices to insure conditions for life will be favorable for people everywhere.

  8. Interactions among rice ORC subunits.

    PubMed

    Tan, Deyong; Lv, Qundan; Chen, Xinai; Shi, Jianghua; Ren, Meiyan; Wu, Ping; Mao, Chuanzao

    2013-08-01

    The origin recognition complex (ORC) is composed of six subunits and plays an important role in DNA replication in all eukaryotes. The ORC subunits OsORC6 as well as the other five ORC subunits in rice were experimentally isolated and sequenced. It indicated that there also exist six ORC subunits in rice. Results of RT-PCR indicated that expression of all the rice ORC genes are no significant difference under 26°C and 34°C. Yeast two hybridization indicated that OsORC2, -3, -5 interact with each other. OsORC5 can then bind OsORC4 to form the OsORC2, -3,-4,-5 core complex. It suggested that the basic interactions have been conserved through evolution. No binding of OsORC1 and OsORC6 with the other subunits were observed. A model of ORC complex in rice is proposed.

  9. Rice scene radiation research plan

    NASA Technical Reports Server (NTRS)

    Heilman, J.

    1982-01-01

    Data requirements, tasks to be accomplished, and the technical approaches to be used in identifying the characteristics of rice for crop inventories are listed as well as methods for estimating crop development and assessing its conditions.

  10. Holocene relative sea levels and related prehistoric activity in the Forth lowland, Scotland, United Kingdom

    NASA Astrophysics Data System (ADS)

    Smith, D. E.; Davies, M. H.; Brooks, C. L.; Mighall, T. M.; Dawson, S.; Rea, B. R.; Jordan, J. T.; Holloway, L. K.

    2010-08-01

    Changes in relative sea level (RSL) and their effect on the distribution of human activity in the Forth lowland, Scotland, UK between ca 11,700 and ca 2000 calibrated years before present (BP) are examined. Block uplift of shorelines occurred over a longer period than previously thought, continuing to at least around 4700 BP. New graphs of RSL change, based upon an analysis of previous work and evidence from new sites using standard morphological and stratigraphical analyses, support a fall in RSL in the early Holocene during which buried estuarine surfaces were formed, followed by a marked reversal on a centennial, perhaps even decadal, scale sometime around 9900-9500 BP from a falling sequence to a rising one. There may have been a short-lived fluctuation in the rising RSL ca 8300 BP, and the Holocene Storegga Slide tsunami of ca 8100 BP was widespread in the lowland. The rising RSL culminated at the Main Postglacial Shoreline, reached ca 7800 BP, when Mean High Water Spring Tides (MHWS) lay within the range 14.6-16.5 m British Ordnance Datum (OD) in the western lowland. This is the highest published Holocene RSL in Britain and Ireland. The subsequent fall in RSL stabilised at a second shoreline, the Blairdrummond Shoreline, from which regression was occurring at ca 4700 BP. RSL later fell to a lower shoreline at ca 3900 BP before reaching present levels within the last three millennia. Comparison between the empirical evidence for RSL change in this area and glacial isostatic adjustment models indicates both similarities and differences. Records of archaeological sites and artefacts in the lowland and surrounding areas are discussed. Maps showing the evolution of the estuary are compared with the distribution of Mesolithic, Neolithic, Bronze Age and Iron Age activity. Evidence for Mesolithic people indicates the opportunistic use of available resources as RSL rose and the estuary expanded to its maximum extent. Neolithic people were also attracted to the estuary

  11. Mars: the evolutionary history of the northern lowlands based on crater counting and geologic mapping

    USGS Publications Warehouse

    Werner, S.C.; Tanaka, K.L.; Skinner, J.A.

    2011-01-01

    The geologic history of planetary surfaces is most effectively determined by joining geologic mapping and crater counting which provides an iterative, qualitative and quantitative method for defining relative ages and absolute model ages. Based on this approach, we present spatial and temporal details regarding the evolution of the Martian northern plains and surrounding regions. The highland–lowland boundary (HLB) formed during the pre-Noachian and was subsequently modified through various processes. The Nepenthes Mensae unit along the northern margins of the cratered highlands, was formed by HLB scarp-erosion, deposition of sedimentary and volcanic materials, and dissection by surface runoff between 3.81 and 3.65 Ga. Ages for giant polygons in Utopia and Acidalia Planitiae are ~ 3.75 Ga and likely reflect the age of buried basement rocks. These buried lowland surfaces are comparable in age to those located closer to the HLB, where a much thinner, post-HLB deposit is mapped. The emplacement of the most extensive lowland surfaces ended between 3.75 and 3.4 Ga, based on densities of craters generally View the MathML source> 3 km in diameter. Results from the polygonal terrain support the existence of a major lowland depocenter shortly after the pre-Noachian formation of the northern lowlands. In general, northern plains surfaces show gradually younger ages at lower elevations, consistent local to regional unit emplacement and resurfacing between 3.6 and 2.6 Ga. Elevation levels and morphology are not necessarily related, and variations in ages within the mapped units are found, especially in units formed and modified by multiple geological processes. Regardless, most of the youngest units in the northern lowlands are considered to be lavas, polar ice, or thick mantle deposits, arguing against the ocean theory during the Amazonian Period (younger than about 3.15 Ga). All ages measured in the closest vicinity of the steep dichotomy escarpment are also 3.7 Ga or

  12. Storage stability of flour-blasted brown rice

    USDA-ARS?s Scientific Manuscript database

    Brown rice was blasted with rice flour rather than sand in a sand blaster to make microscopic nicks and cuts so that water can easily penetrate into the brown rice endosperm and cook the rice in a shorter time. The flour-blasted American Basmati brown rice, long grain brown rice, and parboiled long...

  13. Differentiation of weedy traits in ALS-resistant red rice

    USDA-ARS?s Scientific Manuscript database

    Red rice is a weedy form of cultivated rice (Oryza sativa) that competes aggressively with rice in the southern U.S., reduces yields and contaminates rice grains. The introduction of ClearfieldTM rice, a nontransgenic, herbicide-resistant rice cultivar a decade ago has led to increased use of imazet...

  14. Quantifying the impact of climate change on crop yield and water footprint of rice in the Nam Oon Irrigation Project, Thailand.

    PubMed

    Shrestha, Sangam; Chapagain, Ranju; Babel, Mukand S

    2017-12-01

    Northeast Thailand makes a significant contribution to fragrant and high-quality rice consumed within Thailand and exported to other countries. The majority of rice is produced in rainfed conditions while irrigation water is supplied to rice growers in the dry season. This paper quantifies the potential impact of climate change on the water footprint of rice production using the DSSAT (CERES-Rice) crop growth model for the Nam Oon Irrigation Project located in Northeast Thailand. Crop phenology data was obtained from field experiments and used to set up and validate the CERES-Rice model. The present and future water footprint of rice, the amount of water evaporated during the growing period, was calculated under current and future climatic condition for the irrigation project area. The outputs of three regional climate models (ACCESS-CSIRO-CCAM, CNRM-CM5-CSIRO-CCAM, and MPI-ESM-LR-CSIRO-CCAM) for scenarios RCP 4.5 and RCP 8.5 were downscaled using quantile mapping method. Simulation results show a considerably high increase in the water footprint of KDML-105 and RD-6 rice varieties ranging from 56.5 to 92.2% and 27.5 to 29.7%. respectively for the future period under RCP 4.5, and 71.4 to 76.5% and 27.9 to 37.6%, respectively under RCP 8.5 relative to the simulated baseline water footprint for the period 1976-2005. Conversely, the ChaiNat-1 variety shows a decrease in projected water footprint of 42.1 to 39.4% under RCP 4.5 and 38.5 to 31.7% under RCP 8.5. The results also indicate a huge increase in the future blue water footprint, which will consequently cause a high increment in the irrigation water requirement in order to meet the plant's evaporation demand. The research outcome highlights the importance of proper adaptation strategies to reduce or maintain acceptable water footprints under future climate conditions. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Increasing rice plant growth by Trichoderma sp.

    NASA Astrophysics Data System (ADS)

    Doni, Febri; Isahak, Anizan; Zain, Che Radziah Che Mohd; Sulaiman, Norela; Fathurahman, F.; Zain, Wan Nur Syazana Wan Mohd.; Kadhimi, Ahsan A.; Alhasnawi, Arshad Naji; Anhar, Azwir; Yusoff, Wan Mohtar Wan

    2016-11-01

    Trichoderma sp. is a plant growth promoting fungi in many crops. Initial observation on the ability to enhance rice germination and vigor have been reported. In this study, the effectiveness of a local isolate Trichoderma asprellum SL2 to enhance rice seedling growth was assessed experimentally under greenhouse condition using a completely randomized design. Results showed that inoculation of rice plants with Trichoderma asprellum SL2 significantly increase rice plants height, root length, wet weight, leaf number and biomass compared to untreated rice plants (control). The result of this study can serve as a reference for further work on the application of beneficial microorganisms to enhance rice production.

  16. Detection algorithm for multiple rice seeds images

    NASA Astrophysics Data System (ADS)

    Cheng, F.; Ying, Y. B.

    2006-10-01

    The objective of this research is to develop a digital image analysis algorithm for detection of multiple rice seeds images. The rice seeds used for this study involved a hybrid rice seed variety. Images of multiple rice seeds were acquired with a machine vision system for quality inspection of bulk rice seeds, which is designed to inspect rice seeds on a rotating disk with a CCD camera. Combining morphological operations and parallel processing gave improvements in accuracy, and a reduction in computation time. Using image features selected based on classification ability; a highly acceptable defects classification was achieved when the algorithm was implemented for all the samples to test the adaptability.

  17. [Rice allelopathy to barnyardgrass].

    PubMed

    Xu, Zhenghao; Yu, Liuqing; Zhao, Ming

    2003-05-01

    138 rice (Oryza sativa) germplasms were identified to study the allelopathy to barnyardgrass (Echinochloa crusgalli), using the relay seeding technique. The results showed that Qingkun 2 from Jiangxi Province, Xiayitiao from Jiangsu Province, Jizaoxian from Anhui Province, Ganzaoxian 37 from Jiangxi Province, Shangnuo 1, IR68465-2-3-2 from IRRI, and Shuiyuan 2 from Korea had a strongly excellent inhibition effect on barnyardgrass. Results from pot culture showed that Gumei 2 and Zhong 156 had a greater inhibitory effect than control, and allelopathic material TN1 had no significantly inhibition effect, compared to non-allelopathic material Xiushui 63. The effect of Zhong 156 was related to its plant height, and significant different from that of Xiushui 63. Gumei 2 had a stronger inhibition effect on barnyardgrass, due to its own allelopathic trait.

  18. Nitrification inhibition activity, a novel trait in root exudates of rice

    PubMed Central

    Pariasca Tanaka, Juan; Nardi, Pierfrancesco; Wissuwa, Matthias

    2010-01-01

    Background and aims Nitrification is an important process in soil--plant systems for providing plant-available nitrate (NO3−). However, NO3− is less stable in soils compared with ammonium (NH4+) and is more easily lost through leaching, runoff or denitrification. This study tested whether biological nitrification inhibition (BNI) activity is present in the root exudates of rice (Oryza sativa) and also the extent of variation between different genotypes. Methodology The BNI activity of root exudates was estimated by a bioluminescence assay using a recombinant Nitrosomonas europaea strain. Afterwards, the effect of a single application of concentrated root exudates and that of exudates deposited in the rhizosphere soil was tested on BNI using soil incubation. Soil was added with (NH4)2SO4 and water to reach 60 % of the water-holding capacity and incubated at 30 °C for different periods. Amounts of NH4+ and NO3− were determined using a continuous-flow auto-analyser. Principal results In an initial screening experiment, BNI activity in the exudates of 36 different rice genotypes was evaluated using a bioassay based on a recombinant Nitrosomonas strain. Significant genotypic variation was detected with the upland cultivar IAC25 demonstrating consistently high BNI activity, while modern lowland varieties like Nipponbare or IR64 exhibited lower activity. Subsequent experiments ruled out the possibility that BNI activity is simply due to non-specific (solute) leakage from roots. Soil incubation studies with concentrated root exudates of IAC25 showed significant reductions in NO3− formation. This effect was confirmed by detecting lower NO3− levels in incubation experiments using rhizosphere soil obtained from IAC25. Conclusions Our results provide first evidence that root exudates of rice can reduce nitrification rates in soil. Having shown this for a model crop, rice, offers possibilities for further exploitation of this phenomenon through molecular and genetic

  19. Aerenchyma formation in the rice stem and its promotion by H2O2.

    PubMed

    Steffens, Bianka; Geske, Thomas; Sauter, Margret

    2011-04-01

    • Gas spaces (aerenchyma) form as an adaptation to submergence to facilitate gas exchange. In rice (Oryza sativa), aerenchyma develop by cell death and lysis, which are poorly understood at the cellular level. • Aerenchyma formation was studied in rice stems by light microscopy. It was analyzed in response to submergence, ethylene and hydrogen peroxide (H(2)O(2)) treatment, and in the MT2b::Tos17 mutant. O(2)·(-) was detected with nitroblue tetrazolium and an epinephrine assay. H(2)O(2) was detected with 3,3'-diaminobenzidine. • Aerenchyma develop constitutively in all internodes of the deep-water rice variety Pin Gaew 56, but are absent from the nodes. Constitutive aerenchyma formation was also observed in two lowland rice varieties, albeit to a lesser degree. A larger number of aerenchyma are present in older internodes, and at the top of each internode, revealing developmental gradients. Submergence or treatment with the ethylene-releasing compound ethephon promoted aerenchyma formation in all genotypes analyzed. Pre-aerenchymal cells contain less starch, no chloroplasts, thinner cell walls and produce elevated levels of O(2)·(-) and H(2)O(2) compared with other parenchymal cells. Ethephon promotes O(2)·(-) formation and H(2)O(2) promotes aerenchyma formation in a dose-dependent manner. Further-more, genetic downregulation of the H(2)O(2) scavenger MT2b enhances aerenchyma formation. • Aerenchyma formation is mediated by reactive oxygen species. © The Authors (2010). Journal compilation © New Phytologist Trust (2010).

  20. Multiple abiotic stimuli are integrated in the regulation of rice gene expression under field conditions

    PubMed Central

    Plessis, Anne; Hafemeister, Christoph; Wilkins, Olivia; Gonzaga, Zennia Jean; Meyer, Rachel Sarah; Pires, Inês; Müller, Christian; Septiningsih, Endang M; Bonneau, Richard; Purugganan, Michael

    2015-01-01

    Plants rely on transcriptional dynamics to respond to multiple climatic fluctuations and contexts in nature. We analyzed the genome-wide gene expression patterns of rice (Oryza sativa) growing in rainfed and irrigated fields during two distinct tropical seasons and determined simple linear models that relate transcriptomic variation to climatic fluctuations. These models combine multiple environmental parameters to account for patterns of expression in the field of co-expressed gene clusters. We examined the similarities of our environmental models between tropical and temperate field conditions, using previously published data. We found that field type and macroclimate had broad impacts on transcriptional responses to environmental fluctuations, especially for genes involved in photosynthesis and development. Nevertheless, variation in solar radiation and temperature at the timescale of hours had reproducible effects across environmental contexts. These results provide a basis for broad-based predictive modeling of plant gene expression in the field. DOI: http://dx.doi.org/10.7554/eLife.08411.001 PMID:26609814

  1. Expansins in deepwater rice internodes.

    PubMed

    Cho, H T; Kende, H

    1997-04-01

    Cell walls of deepwater rice (Oryza sativa L.) internodes undergo long-term extension (creep) when placed under tension in acidic buffers. This is indicative of the action of the cell wall-loosening protein expansin. Wall extension had a pH optimum of around 4.0 and was abolished by boiling. Acid-induced extension of boiled cell walls could be reconstituted by addition of salt-extracted rice or cucumber cell wall proteins. Cucumber expansin antibody recognized a single protein band of 24.5-kD apparent molecular mass on immunoblots of rice cell wall proteins. Expansins were partially purified by concanavalin A affinity chromatography and sulfopropyl (SP) cation-exchange chromatography. The latter yielded two peaks with extension activity (SP20 and SP29), and immunoblot analysis showed that both of these active fractions contained expansin of 24.5-kD molecular mass. The N-terminal amino acid sequence of SP20 expansin is identical to that deduced from the rice expansin cDNA Os-EXP1. The N-terminal amino acid sequence of SP29 expansin matches that deduced from the rice expansin cDNA Os-EXP2 in six of eight amino acids. Our results show that two expansins occur in the cell walls of rice internodes and that they may mediate acid-induced wall extension.

  2. Kennedy at Rice University

    NASA Technical Reports Server (NTRS)

    1962-01-01

    President Kennedy speaks before a crowd of 35,000 people at Rice University in the football field. The following are excerpts from his speech. ' ...We set sail on his new sea because there is a new knowledge to begained, and new rights to be won, and they must be won and used for the progress of all people. Whether it will become a force for good or ill depends on man, and only if the United States occupies a position of pre-eminence can we help decide whether this new ocean will be a sea of peace or a new terrifying theater of war. But I do say space can be explored and mastered without feeding the fires of war, without repeating the mistakes that man has made with extending his wirt around this globe of ours. There is no strife, no prejudice, no national conflict in outer space as yet. Its conquest deserves the best of all mankind, and its opportunity for peaceful cooperation may never come again. But why, some say the Moon? Why choose this as our goal? And they may well ask, why climb the highest mountain? Why 35 years ago why fly the Atlantic? Why does Rice play Texas? We choose to go to the Moon, we choose to go to the moon in this decade and do the other things, not because they are easy, but because they are hard, because that goal will serve to organize and measure the best of our energies and skills, because that challenge is one that we are willing to accept, one we are unwilling to postpone, and one in which we attend to win, and the others , too.'

  3. Pullulanase from rice endosperm.

    PubMed

    Yamasaki, Yoshiki; Nakashima, Susumu; Konno, Haruyoshi

    2008-01-01

    Pullulanase (EC 3.2.1.41) in non-germinating seeds was compared with that in germinating seeds. Moreover, pullulanase from the endosperm of rice (Oryza sativa L., cv. Hinohikari) seeds was isolated and its properties investigated. The pI value of pullulanase from seeds after 8 days of germination was almost equal to that from non-germinating seeds, which shows that these two enzymes are the same protein. Therefore, the same pullulanase may play roles in both starch synthesis during ripening and starch degradation during germination in rice seeds. The enzyme was isolated by a procedure that included ammonium sulfate fractionation, DEAE-cellulofine column chromatography, preparative isoelectric focusing, and preparative disc gel electrophoresis. The enzyme was homogeneous by SDS/PAGE. The molecular weight of the enzyme was estimated to be 100 000 based on its mobility on SDS/PAGE and 105 000 based on gel filtration with TSKgel super SW 3000, which showed that it was composed of a single unit. The isoelectric point of the enzyme was 4.7. The enzyme was strongly inhibited by beta-cyclodextrin. The enzyme was not activated by thiol reagents such as dithiothreitol, 2-mercaptoethanol or glutathione. The enzyme most preferably hydrolyzed pullulan and liberated only maltotriose. The pullulan hydrolysis was strongly inhibited by the substrate at a concentration higher than 0.1%. The degree of inhibition increased with an increase in the concentration of pullulan. However, the enzyme hydrolyzed amylopectin, soluble starch and beta-limit dextrin more rapidly as their concentrations increased. The enzyme exhibited alpha-glucosyltransfer activity and produced an alpha-1,6-linked compound of two maltotriose molecules from pullulan.

  4. Kennedy at Rice University

    NASA Technical Reports Server (NTRS)

    1962-01-01

    President Kennedy speaks before a crowd of 35,000 people at Rice University in the football field. The following are excerpts from his speech. ' ...We set sail on his new sea because there is a new knowledge to be gained, and new rights to be won, and they must be won and used for the progress of all people. ...Whether it will become a force for good or ill depends on man, and only if the United States occupies a position of pre-eminence can we help decide whether this new ocean will be a sea of peace or a new terrifying theater of war. But I do say space can be explored and mastered without feeding the fires of war, without repeating the mistakes that man has made with extending his writ around this globe of ours. ...There is no strife, no prejudice, no national conflict in outer space as yet. Its conquest deserves the best of all mankind, and its opportunity for peaceful cooperation may never come again. But why, some say the Moon? Why choose this as our goal? And they may well ask, why climb the highest mountian? Why - 35 years ago - why fly the Atlantic? Why does Rice play Texas? We choose to go to the Moon, we choose to go to the Moon in this decade and do the other things, not because they are easy, but because they are hard, because that goal will serve to organize and measure the best of our energies and skills, because that challenge is one that we are willing to accept, one we are unwilling to postpone, and one in which we intend to win, and the others too.'

  5. [Causes of drinking-water contamination in rain-fed cisterns in three villages in Ramallah and Al-Bireh District, Palestine].

    PubMed

    Al-Khatib, Issam A; Orabi, Moammar

    2004-05-01

    We studied the biological characteristics of drinking-water in three villages in Ramallah and al-Bireh district, by testing the total coliforms. Water samples were collected from rain-fed cisterns between October and November 2001. The results show that 87% of tested samples of drinking-water were highly contaminated and in need of coagulation, filtration and disinfection based on the World Health Organization guidelines for drinking-water, and 10.5% had low contamination and were in need of treatment by disinfection only. Only 2.5% of the tested samples were not contaminated and were suitable for drinking without treatment. The main cause of drinking-water con tamination was the presence of cesspits, wastewater and solid waste dumping sites near the cisterns.

  6. Red rice (Oryza sativa L.) emergence characteristics and influence on rice (O. sativa) yield at different planting dates

    USDA-ARS?s Scientific Manuscript database

    Cultivated rice yield losses due to red rice infestation vary by cultivar, red rice density, and duration of interference. The competition effects of red rice could be influenced further by emergence characteristics, red rice biotype, and planting time of cultivated rice. We aimed to characterize th...

  7. 7 CFR 319.55a - Administrative instructions relating to entry of rice straw and rice hulls into Guam.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... straw and rice hulls into Guam. 319.55a Section 319.55a Agriculture Regulations of the Department of... QUARANTINE NOTICES Rice Quarantine § 319.55a Administrative instructions relating to entry of rice straw and rice hulls into Guam. Rice straw and rice hulls may be imported into Guam without further permit, other...

  8. 7 CFR 319.55a - Administrative instructions relating to entry of rice straw and rice hulls into Guam.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... straw and rice hulls into Guam. 319.55a Section 319.55a Agriculture Regulations of the Department of... QUARANTINE NOTICES Rice Quarantine § 319.55a Administrative instructions relating to entry of rice straw and rice hulls into Guam. Rice straw and rice hulls may be imported into Guam without further permit, other...

  9. Genetic analysis of atypical U.S. red rice phenotypes: indications of prior gene flow in rice fields?

    USDA-ARS?s Scientific Manuscript database

    Red rice is a troublesome weed problem in rice fields of the southern U.S. Outcrossing between rice and red rice occurs at low rates, resulting in a broad array of plant types. SSR markers were used to evaluate the genetic backgrounds of atypical red rice types obtained from rice farms in comparis...

  10. Outcrossing potential between U.S. red rice (Oryza sativa) and Chinese indica rice (Oryza sativa) lines

    USDA-ARS?s Scientific Manuscript database

    Red rice in southern U.S. rice fields remains a widespread, economically challenging problem despite nearly a decade of rice production systems that include true-breeding rice cultivars and indica-derived hybrid rice with resistance to imazethapyr. Both of these herbicide-resistant rice systems hav...

  11. Harnessing the hidden genetic diversity for improving multiple abiotic stress tolerance in rice (Oryza sativa L.)

    PubMed Central

    Gao, Yong-Ming; Ma, Xiu-Fang; Meng, Li-Jun; Wang, Ying; Pang, Yun-Long; Guan, Yong-Sheng; Xu, Mei-Rong; Revilleza, Jastin E.; Franje, Neil J.; Zhou, Shao-Chuan; Li, Zhi-Kang

    2017-01-01

    To develop superior rice varieties with improved yield in most rainfed areas of Asia/Africa, we started an introgression-breeding program for simultaneously improving yield and tolerances of multiple abiotic stresses. Using eight BC1 populations derived from a widely adaptable recipient and eight donors plus three rounds of phenotypic selection, we developed 496 introgression lines (ILs) with significantly higher yield under drought, salt and/or non-stress conditions in 5 years. Six new varieties were released in the Philippines and Pakistan and many more are being evaluated in multi-location yield trials for releasing in several countries. Marker-facilitated genetic characterization revealed three interesting aspects of the breeding procedure: (1) the donor introgression pattern in specific BC populations was characteristic; (2) introgression frequency in different genomic regions varied considerably, resulting primarily from strong selection for the target traits; and (3) significantly lower heterozygosity was observed in BC progenies selected for drought and salinity tolerance. Applying strong phenotypic selection under abiotic stresses in early segregating generations has major advantages for not only improving multiple abiotic stress tolerance but also achieving quicker homozygosity in early generations. This breeding procedure can be easily adopted by small breeding programs in developing countries to develop high-yielding varieties tolerant of abiotic stresses. The large set of trait-specific ILs can be used for genetic mapping of genes/QTL that affect target and non-target traits and for efficient varietal development by designed QTL pyramiding and genomics-based recurrent selection in our Green Super Rice breeding technology. PMID:28278154

  12. Harnessing the hidden genetic diversity for improving multiple abiotic stress tolerance in rice (Oryza sativa L.).

    PubMed

    Ali, Jauhar; Xu, Jian-Long; Gao, Yong-Ming; Ma, Xiu-Fang; Meng, Li-Jun; Wang, Ying; Pang, Yun-Long; Guan, Yong-Sheng; Xu, Mei-Rong; Revilleza, Jastin E; Franje, Neil J; Zhou, Shao-Chuan; Li, Zhi-Kang

    2017-01-01

    To develop superior rice varieties with improved yield in most rainfed areas of Asia/Africa, we started an introgression-breeding program for simultaneously improving yield and tolerances of multiple abiotic stresses. Using eight BC1 populations derived from a widely adaptable recipient and eight donors plus three rounds of phenotypic selection, we developed 496 introgression lines (ILs) with significantly higher yield under drought, salt and/or non-stress conditions in 5 years. Six new varieties were released in the Philippines and Pakistan and many more are being evaluated in multi-location yield trials for releasing in several countries. Marker-facilitated genetic characterization revealed three interesting aspects of the breeding procedure: (1) the donor introgression pattern in specific BC populations was characteristic; (2) introgression frequency in different genomic regions varied considerably, resulting primarily from strong selection for the target traits; and (3) significantly lower heterozygosity was observed in BC progenies selected for drought and salinity tolerance. Applying strong phenotypic selection under abiotic stresses in early segregating generations has major advantages for not only improving multiple abiotic stress tolerance but also achieving quicker homozygosity in early generations. This breeding procedure can be easily adopted by small breeding programs in developing countries to develop high-yielding varieties tolerant of abiotic stresses. The large set of trait-specific ILs can be used for genetic mapping of genes/QTL that affect target and non-target traits and for efficient varietal development by designed QTL pyramiding and genomics-based recurrent selection in our Green Super Rice breeding technology.

  13. Natural rice rhizospheric microbes suppress rice blast infections

    PubMed Central

    2014-01-01

    Background The natural interactions between plant roots and their rhizospheric microbiome are vital to plant fitness, modulating both growth promotion and disease suppression. In rice (Oryza sativa), a globally important food crop, as much as 30% of yields are lost due to blast disease caused by fungal pathogen Magnaporthe oryzae. Capitalizing on the abilities of naturally occurring rice soil bacteria to reduce M. oryzae infections could provide a sustainable solution to reduce the amount of crops lost to blast disease. Results Naturally occurring root-associated rhizospheric bacteria were isolated from California field grown rice plants (M-104), eleven of which were taxonomically identified by16S rRNA gene sequencing and fatty acid methyl ester (FAME) analysis. Bacterial isolates were tested for biocontrol activity against the devastating foliar rice fungal pathogen, M. oryzae pathovar 70–15. In vitro, a Pseudomonas isolate, EA105, displayed antibiosis through reducing appressoria formation by nearly 90% as well as directly inhibiting fungal growth by 76%. Although hydrogen cyanide (HCN) is a volatile commonly produced by biocontrol pseudomonads, the activity of EA105 seems to be independent of its HCN production. During in planta experiments, EA105 reduced the number of blast lesions formed by 33% and Pantoea agglomerans isolate, EA106 by 46%. Our data also show both EA105 and EA106 trigger jasmonic acid (JA) and ethylene (ET) dependent induced systemic resistance (ISR) response in rice. Conclusions Out of 11 bacteria isolated from rice soil, pseudomonad EA105 most effectively inhibited the growth and appressoria formation of M. oryzae through a mechanism that is independent of cyanide production. In addition to direct antagonism, EA105 also appears to trigger ISR in rice plants through a mechanism that is dependent on JA and ET signaling, ultimately resulting in fewer blast lesions. The application of native bacteria as biocontrol agents in combination with

  14. SNP-Based QTL Mapping of 15 Complex Traits in Barley under Rain-Fed and Well-Watered Conditions by a Mixed Modeling Approach

    PubMed Central

    Mora, Freddy; Quitral, Yerko A.; Matus, Ivan; Russell, Joanne; Waugh, Robbie; del Pozo, Alejandro

    2016-01-01

    This study identified single nucleotide polymorphism (SNP) markers associated with 15 complex traits in a breeding population of barley (Hordeum vulgare L.) consisting of 137 recombinant chromosome substitution lines (RCSL), evaluated under contrasting water availability conditions in the Mediterranean climatic region of central Chile. Given that markers showed a very strong segregation distortion, a quantitative trait locus/loci (QTL) mapping mixed model was used to account for the heterogeneity in genetic relatedness between genotypes. Fifty-seven QTL were detected under rain-fed conditions, which accounted for 5–22% of the phenotypic variation. In full irrigation conditions, 84 SNPs were significantly associated with the traits studied, explaining 5–35% of phenotypic variation. Most of the QTL were co-localized on chromosomes 2H and 3H. Environment-specific genomic regions were detected for 12 of the 15 traits scored. Although most QTL-trait associations were environment and trait specific, some important and stable associations were also detected. In full irrigation conditions, a relatively major genomic region was found underlying hectoliter weight (HW), on chromosome 1H, which explained between 27% (SNP 2711-234) and 35% (SNP 1923-265) of the phenotypic variation. Interestingly, the locus 1923-265 was also detected for grain yield at both environmental conditions, accounting for 9 and 18%, in the rain-fed and irrigation conditions, respectively. Analysis of QTL in this breeding population identified significant genomic regions that can be used for marker-assisted selection (MAS) of barley in areas where drought is a significant constraint. PMID:27446139

  15. SNP-Based QTL Mapping of 15 Complex Traits in Barley under Rain-Fed and Well-Watered Conditions by a Mixed Modeling Approach.

    PubMed

    Mora, Freddy; Quitral, Yerko A; Matus, Ivan; Russell, Joanne; Waugh, Robbie; Del Pozo, Alejandro

    2016-01-01

    This study identified single nucleotide polymorphism (SNP) markers associated with 15 complex traits in a breeding population of barley (Hordeum vulgare L.) consisting of 137 recombinant chromosome substitution lines (RCSL), evaluated under contrasting water availability conditions in the Mediterranean climatic region of central Chile. Given that markers showed a very strong segregation distortion, a quantitative trait locus/loci (QTL) mapping mixed model was used to account for the heterogeneity in genetic relatedness between genotypes. Fifty-seven QTL were detected under rain-fed conditions, which accounted for 5-22% of the phenotypic variation. In full irrigation conditions, 84 SNPs were significantly associated with the traits studied, explaining 5-35% of phenotypic variation. Most of the QTL were co-localized on chromosomes 2H and 3H. Environment-specific genomic regions were detected for 12 of the 15 traits scored. Although most QTL-trait associations were environment and trait specific, some important and stable associations were also detected. In full irrigation conditions, a relatively major genomic region was found underlying hectoliter weight (HW), on chromosome 1H, which explained between 27% (SNP 2711-234) and 35% (SNP 1923-265) of the phenotypic variation. Interestingly, the locus 1923-265 was also detected for grain yield at both environmental conditions, accounting for 9 and 18%, in the rain-fed and irrigation conditions, respectively. Analysis of QTL in this breeding population identified significant genomic regions that can be used for marker-assisted selection (MAS) of barley in areas where drought is a significant constraint.

  16. The combined and separate impacts of climate extremes on the current and future US rainfed maize and soybean production under elevated CO2.

    PubMed

    Jin, Zhenong; Zhuang, Qianlai; Wang, Jiali; Archontoulis, Sotirios V; Zobel, Zachary; Kotamarthi, Veerabhadra R

    2017-01-07

    Heat and drought are two emerging climatic threats to the US maize and soybean production, yet their impacts on yields are collectively determined by the magnitude of climate change and rising atmospheric CO2 concentrations. This study quantifies the combined and separate impacts of high temperature, heat and drought stresses on the current and future US rainfed maize and soybean production and for the first time characterizes spatial shifts in the relative importance of individual stress. Crop yields are simulated using the Agricultural Production Systems Simulator (APSIM), driven by high-resolution (12 km) dynamically downscaled climate projections for 1995-2004 and 2085-2094. Results show that maize and soybean yield losses are prominent in the US Midwest by the late 21st century under both Representative Concentration Pathway (RCP) 4.5 and RCP8.5 scenarios, and the magnitude of loss highly depends on the current vulnerability and changes in climate extremes. Elevated atmospheric CO2 partially but not completely offsets the yield gaps caused by climate extremes, and the effect is greater in soybean than in maize. Our simulations suggest that drought will continue to be the largest threat to US rainfed maize production under RCP4.5 and soybean production under both RCP scenarios, whereas high temperature and heat stress take over the dominant stress of drought on maize under RCP8.5. We also reveal that shifts in the geographic distributions of dominant stresses are characterized by the increase in concurrent stresses, especially for the US Midwest. These findings imply the importance of considering heat and drought stresses simultaneously for future agronomic adaptation and mitigation strategies, particularly for breeding programs and crop management. The modeling framework of partitioning the total effects of climate change into individual stress impacts can be applied to the study of other crops and agriculture systems.

  17. Chlorophyll fluorescence induction kinetics and yield responses in rainfed crops with variable potassium nutrition in K deficient semi-arid alfisols.

    PubMed

    Srinivasarao, Ch; Shanker, Arun K; Kundu, Sumanta; Reddy, Sharanbhoopal

    2016-07-01

    Optimum potassium (K) nutrition in semi-arid regions may help crop plants to overcome constraints in their growth and development such as moisture stress, leading to higher productivity of rainfed crops, thus judicious K management is essential. A study was conducted to evaluate the importance of K nutrition on physiological processes like photosynthesis through chlorophyll a fluorescence and chlorophyll fluorescence induction kinetics (OJIP) of rainfed crops viz., maize (Zea mays L.), pearl millet (Pennisetum glaucum), groundnut (Arachis hypogaea), sunflower (Helianthus annuus), castor (Ricinus communis L.) and cotton (Gossypium hirsutum) under water stress conditions by studying their growth attributes, water relations, yield, K uptake and use efficiency under varied K levels. Highest chlorophyll content was observed under K60 in maize and pearl millet. Narrow and wide Chl a:b ratio was observed in castor and groundnut respectively. The fluorescence yield decreased in the crops as K dosage increased, evidenced by increasing of all points (O, J, I and P) of the OJIP curves. The fluorescence transient curve for K60 was lower than K0 and K40 for all the crops. Potassium levels altered the fluorescence induction and impaired photosynthetic systems in all the crops studied. There was no distinct trend observed in leaf water potential of crops under study. Uptake of K was high in sunflower with increased rate of K application. Quantitatively, K uptake by castor crop was lesser compared to all other crops. Our results indicate that the yield reduction under low K was due to the low capacity of the crops to translocate K from non-photosynthetic organs such as stems and petioles to upper leaves and harvested organs and this in turn influenced the capacity of the crops to produce a high economic yield per unit of K taken up thus reducing utilization efficiency of K.

  18. A tillering inhibition gene influences root–shoot carbon partitioning and pattern of water use to improve wheat productivity in rainfed environments

    PubMed Central

    Hendriks, P.W.; Kirkegaard, J.A.; Lilley, J.M.; Gregory, P.J.; Rebetzke, G.J.

    2016-01-01

    Genetic modification of shoot and root morphology has potential to improve water and nutrient uptake of wheat crops in rainfed environments. Near-isogenic lines (NILs) varying for a tillering inhibition (tin) gene and representing multiple genetic backgrounds were phenotyped in contrasting, controlled environments for shoot and root growth. Leaf area, shoot and root biomass were similar until tillering, whereupon reduced tillering in tin-containing NILs produced reductions of up to 60% in total leaf area and biomass, and increases in total root length of up to 120% and root biomass to 145%. Together, the root-to-shoot ratio increased two-fold with the tin gene. The influence of tin on shoot and root growth was greatest in the cv. Banks genetic background, particularly in the biculm-selected NIL, and was typically strongest in cooler environments. A separate de-tillering study confirmed greater root-to-shoot ratios with regular tiller removal in non-tin-containing genotypes. In validating these observations in a rainfed field study, the tin allele had a negligible effect on seedling growth but was associated with significantly (P<0.05) reduced tiller number (–37%), leaf area index (–26%), and spike number (–35%) to reduce plant biomass (–19%) at anthesis. Root biomass, root-to-shoot ratio at early stem elongation, and root depth at maturity were all increased in tin-containing NILs. Soil water use was slowed in tin-containing NILs, resulting in greater water availability, greater stomatal conductance, cooler canopy temperatures, and maintenance of green leaf area during grain-filling. Together these effects contributed to increases in harvest index and grain yield. In both the controlled and field environments, the tin gene was commonly associated with increased root length and biomass, but the significant influence of genetic background and environment suggests careful assessment of tin-containing progeny in selection for genotypic increases in root growth

  19. Quantitative trait loci for water-use efficiency in barley (Hordeum vulgare L.) measured by carbon isotope discrimination under rain-fed conditions on the Canadian Prairies.

    PubMed

    Chen, Jing; Chang, Scott X; Anyia, Anthony O

    2012-06-01

    Barley (Hordeum vulgare L.) yield is commonly limited by low rainfall and high temperature during the growing season on the Canadian Prairies. Empirical knowledge suggests that carbon isotope discrimination (Δ(13)C), through its negative relationship with water-use efficiency (WUE), is a good index for selecting stable yielding crops in some rain-fed environments. Identification of quantitative trait loci (QTL) and linked markers for Δ(13)C will enhance its use efficiency in breeding programs. In the present study, two barley populations (W89001002003 × I60049 or W × I, six-row type, and Merit × H93174006 or M × H, two-row type), containing 200 and 127 recombinant inbred lines (RILs), were phenotyped for leaf Δ(13)C and agronomic traits under rain-fed environments in Alberta, Canada. A transgressive segregation pattern for leaf Δ(13)C was observed among RILs. The broad-sense heritability (H (2)) of leaf Δ(13)C was 0.8, and there was no significant interaction between genotype and environment for leaf Δ(13)C in the W × I RILs. A total of 12 QTL for leaf Δ(13)C were detected in the W × I RILs and 5 QTL in the M × H RILs. For the W × I RILs, a major QTL located on chromosome 3H near marker Bmag606 (9.3, 9.4 and 10.7 cM interval) was identified. This major QTL overlapped with several agronomic traits, with W89001002003 alleles favoring lower leaf Δ(13)C, increased plant height, and reduced leaf area index, grain yield, harvest index and days to maturity at this locus or loci. This major QTL and its associated marker, when validated, maybe useful in breeding programs aimed at improving WUE and yield stability of barley on the Canadian Prairies.

  20. Processing Conditions, Rice Properties, Health and Environment

    PubMed Central

    Roy, Poritosh; Orikasa, Takahiro; Okadome, Hiroshi; Nakamura, Nobutaka; Shiina, Takeo

    2011-01-01

    Rice is the staple food for nearly two-thirds of the world’s population. Food components and environmental load of rice depends on the rice form that is resulted by different processing conditions. Brown rice (BR), germinated brown rice (GBR) and partially-milled rice (PMR) contains more health beneficial food components compared to the well milled rice (WMR). Although the arsenic concentration in cooked rice depends on the cooking methods, parboiled rice (PBR) seems to be relatively prone to arsenic contamination compared to that of untreated rice, if contaminated water is used for parboiling and cooking. A change in consumption patterns from PBR to untreated rice (non-parboiled), and WMR to PMR or BR may conserve about 43–54 million tons of rice and reduce the risk from arsenic contamination in the arsenic prone area. This study also reveals that a change in rice consumption patterns not only supply more food components but also reduces environmental loads. A switch in production and consumption patterns would improve food security where food grains are scarce, and provide more health beneficial food components, may prevent some diseases and ease the burden on the Earth. However, motivation and awareness of the environment and health, and even a nominal incentive may require for a method switching which may help in building a sustainable society. PMID:21776212

  1. High-resolution lidar topography of the Puget Lowland, Washington - A bonanza for earth science

    USGS Publications Warehouse

    Haugerud, R.A.; Harding, D.J.; Johnson, S.Y.; Harless, J.L.; Weaver, C.S.; Sherrod, B.L.

    2003-01-01

    More than 10,000 km2 of high-resolution, public-domain topography acquired by the Puget Sound Lidar Consortium is revolutionizing investigations of active faulting, continental glaciation, landslides, and surficial processes in the seismically active Puget Lowland. The Lowland-the population and economic center of the Pacific Northwest-presents special problems for hazards investigations, with its young glacial topography, dense forest cover, and urbanization. Lidar mapping during leaf-off conditions has led to a detailed digital model of the landscape beneath the forest canopy. The surface thus revealed contains a rich and diverse record of previously unknown surface-rupturing faults, deep-seated landslides, uplifted Holocene and Pleistocene beaches, and subglacial and periglacial features. More than half a dozen suspected postglacial fault scarps have been identified to date. Five scarps that have been trenched show evidence of large, Holocene, surface-rupturing earthquakes.

  2. Why are There So Few Magnetic Anomalies in Martian Lowlands and Basins?

    NASA Technical Reports Server (NTRS)

    Solomon, Sean C.; Aharonson, Oded; Banerdt, W. Bruce; Dombard, Andrew J.; Frey, Herbert V.; Golombek, Matthew P.; Hauck, Steven A., II; Head, James W., III; Johnson, Catherine L.; McGovern, Patrick J.

    2003-01-01

    The discovery of large areas of strongly magnetized crust on Mars [1,2] provides important information on the timing of both crustal and deeper interior processes on that planet. Critical to an understanding of that timing, as well as to the processes that have contributed to the magnetization and demagnetization of crustal materials, is the geographical distribution of magnetic anomalies discernible from spacecraft orbit. The paucity of resolved magnetic anomalies in the northern lowlands and within and surrounding the best-preserved major impact basins has been noted since the crustal field was first globally mapped [1], but no straightforward explanation of that full pattern has yet been offered. Here we suggest that ancient hydrothermal alteration of magnetic carriers in Martian lowlands and basins may have contributed to the magnetization distribution observed today.

  3. Biodestructive processes occurring in the organic matter of lowland peat in the arctic zone

    NASA Astrophysics Data System (ADS)

    Svarovskaya, L. I.; Altunina, L. K.; Serebrennikova, O. V.

    2016-11-01

    A model experiment was carried on in laboratory conditions. The biodestruction of organic matter was studied using lowland peat samples collected in Kolguev Island in Barents Sea. Here the purpose was to obtain information about the species range and the activity of bacterial complex involved in the destruction processes of lowland peat organic matter from the natural environment by simulating the Arctic zone climate. The species range is found to include bacteria dominant species, i.e. Rhodococcus, Arthrobacter, Bacillus and Pseudomonas. In order to stimulate the biodestruction of organic matter, inoculate was added to the culture medium containing peat; its composition and dose were determined by the trial-and-error method. The catalytic activity of bacterial ferments was initiated in the presence of inoculate; hence, the desired effect was achieved. The composition of the organic matter of bacterial biomass and peat was analyzed by the method of gas chromatography-mass spectrometry.

  4. The impact of planting date on management of the rice water weevil in Louisiana rice

    USDA-ARS?s Scientific Manuscript database

    The rice water weevil, Lissorhoptrus oryzophilus, is the most destructive insect pest of rice in the United States. Early planting of rice to avoid damaging infestations of the rice water weevil has long been suggested as a management tactic. A five-year study was conducted to characterize the influ...

  5. Genetic diversity for rice grain mineral concentrations observed among genetically and geographically giverse rice accessions

    USDA-ARS?s Scientific Manuscript database

    With about half of the world’s people dependent on rice as their main food source, improving the nutritional value of rice could have major impact on human health. While rice in the USA is often artificially fortified, natural enhancement of the rice grain’s nutritional value, i.e. from genetic impr...

  6. Volatiles induction in rice stink bug host grasses and rice plants

    USDA-ARS?s Scientific Manuscript database

    Rice stink bug (RSB), Oebalus pugnax F., is an important pest of heading rice in the United States. Little is known about plant volatiles production following herbivory by the rice stink bug. RSB feeding induced volatiles production in different RSB host grasses and rice varieties, and may help expl...

  7. Diversity of global rice markets and the science required for consumer-targeted rice breeding

    USDA-ARS?s Scientific Manuscript database

    With the ever-increasing global demand for high quality rice in both local production regions and with Western consumers, we have a strong desire to understand better the importance of different quality traits that make up the rice grain and obtain a full picture of rice quality demographics. Rice ...

  8. Utilization of weedy rice for development of japonica hybrid rice (Oryza sativa L.).

    PubMed

    Tang, Liang; Ma, Dian Rong; Xu, Zheng Jin; Deng, Hua Feng; Chen, Wen Fu; Yuan, Long Ping

    2011-05-01

    Two representative weedy rice lines, three typical japonica varieties and three typical indica varieties were used for 6 pairs of reciprocal crosses. The morphological traits of twelve F(1) hybrid lines, their parents and four elite cultivars were investigated for heterosis over mid-parent (HM), over parent (HP) and competitive heterosis (CH) analysis. Traits detected in weedy rice lines seemed larger than those in cultivars and excellent heterosis was produced in weedy rice crossing with japonica rice. Although weedy rice kept closer relationships with japonica rice compared to indica rice. But the heterosis of reciprocal crosses between weedy rice and japonica was closed to those of crosses between indica rice and japonica rice. In six of one hundred and eighteen weedy rice lines, the fertility restore gene for BT type cytoplasmic male sterility (BT-CMS) were detected. Weedy rice was very valuable germplasm resources with the abundant polymorphism. Meanwhile, the disadvantage, lodging, shattering and incompact plant type, should be modified by hybridization, backcross and multiple cross with japonica rice. Although it is difficult to use weedy rice directly, weedy rice may be available to breed both male sterile line and restorer line through improvement, developing japonica hybrid rice.

  9. Elemental composition of Malawian rice.

    PubMed

    Joy, Edward J M; Louise Ander, E; Broadley, Martin R; Young, Scott D; Chilimba, Allan D C; Hamilton, Elliott M; Watts, Michael J

    2017-08-01

    Widespread potential dietary deficiencies of calcium (Ca), iron (Fe), iodine (I), selenium (Se) and zinc (Zn) have been identified in Malawi. Several deficiencies are likely to be compounded by high phytic acid (PA) consumption. Rice (Oryza sativa) is commonly consumed in some Malawian populations, and its mineral micronutrient content is important for food security. The considerable irrigation requirements and flooded conditions of paddy soils can also introduce or mobilise potentially toxic elements including arsenic (As), cadmium (Cd) and lead (Pb). The aim of this study was to determine the mineral composition of rice sampled from farmers' fields and markets in Malawi. Rice was sampled from 18 extension planning areas across Malawi with 21 white (i.e. polished) and 33 brown samples collected. Elemental composition was determined by inductively coupled plasma-mass spectrometry (ICP-MS). Arsenic speciation was performed using high-performance liquid chromatography (HPLC)-ICP-MS. Concentration of PA was determined using a PA-total phosphorus assay. Median total concentrations (mg kg(-1), dry weight) of elements important for human nutrition in brown and white rice, respectively, were: Ca = 66.5 and 37.8; Cu = 3.65 and 2.49; Fe = 22.1 and 7.2; I = 0.006 and <0.005; Mg = 1130 and 265; Mn = 18.2 and 9.6; Se = 0.025 and 0.028; and Zn = 17.0 and 14.4. In brown and white rice samples, respectively, median PA concentrations were 5438 and 1906 mg kg(-1), and median PA:Zn molar ratios were 29 and 13. Concentrations of potentially toxic elements (mg kg(-1), dry weight) in brown and white rice samples, respectively, were: As = 0.030 and 0.006; Cd  ≤ 0.002 and 0.006; Pb = 0.008 and 0.008. Approximately 95 % of As was found to be inorganic As, where this could be quantified. Malawian rice, like the more widely consumed staple grain maize, contains inadequate Ca, I, Se or Zn to meet dietary requirements. Biofortification strategies could

  10. Comparison of rice lines derived through anther culture and the pedigree method in relation to blast (Pyricularia grisea Sacc.) resistance.

    PubMed

    Martínez, C P; Victoria, F C; Amézquita, M C; Tulande, E; Lema, G; Zeigler, R S

    1996-04-01

    Crosses were made between Fanny (highly susceptible to blast) and 11 cultivars differing in blast resistance. Using the pedigree method (PM) segregating generations were evaluated and selected for blast resistance. Via anther culture (AC), doubled-haploids were obtained from F1 plants and from F2 blast-susceptible plants. Pedigree and anther culture-derived lines were planted together and evaluated for blast resistance under rainfed conditions at the Santa Rosa Experiment Station, Villavicencio, Colombia. The principal objective was to compare PM and AC in terms of their efficiency in producing rice lines resistant to blast. Results of a stratified analysis showed an association between method and blast resistance. Results of the logit-model analysis showed that AC produced a significantly (P=0.0001) higher proportion of lines with initial blast resistance (leaf- and neck-blast reaction ≤4) than did PM across all cross types. Stable blast resistance was assessed based on field performance over 3 years. AC was superior to PM in generating stable resistance for only some cross types. Consequently, with a few exceptions, AC can be used as effectively as PM to develop rice cultivars resistant to blast, with savings in time and labor. Additionally, blast-resistant lines were obtained either by the pedigree method or by anther culture from crosses between blast-susceptible cultivars (Fanny/CICA4 and Fanny/Colombial). This excludes somaclonal variation as a possible mechanism responsible for this resistance and suggests that a recombination of minor genes could have occurred and was fixed through either method. However, the stability of the resistance was greater in pedigree-derived lines. The implications of these findings for rice blast-resistance breeding are discussed.

  11. The Lethal Fungus Batrachochytrium dendrobatidis Is Present in Lowland Tropical Forests of Far Eastern Panamá

    PubMed Central

    Rebollar, Eria A.; Hughey, Myra C.; Harris, Reid N.; Domangue, Rickie J.; Medina, Daniel; Ibáñez, Roberto; Belden, Lisa K.

    2014-01-01

    The fungal disease chytridiomycosis, caused by Batrachochytrium dendrobatidis (Bd), is one of the main causes of amphibian population declines and extinctions all over the world. In the Neotropics, this fungal disease has caused catastrophic declines in the highlands as it has spread throughout Central America down to Panamá. In this study, we determined the prevalence and intensity of Bd infection in three species of frogs in one highland and four lowland tropical forests, including two lowland regions in eastern Panamá in which the pathogen had not been detected previously. Bd was present in all the sites sampled with a prevalence ranging from 15–34%, similar to other Neotropical lowland sites. The intensity of Bd infection on individual frogs was low, ranging from average values of 0.11–24 zoospore equivalents per site. Our work indicates that Bd is present in anuran communities in lowland Panamá, including the Darién province, and that the intensity of the infection may vary among species from different habitats and with different life histories. The population-level consequences of Bd infection in amphibian communities from the lowlands remain to be determined. Detailed studies of amphibian species from the lowlands will be essential to determine the reason why these species are persisting despite the presence of the pathogen. PMID:24740162

  12. The lethal fungus Batrachochytrium dendrobatidis is present in lowland tropical forests of far eastern Panamá.

    PubMed

    Rebollar, Eria A; Hughey, Myra C; Harris, Reid N; Domangue, Rickie J; Medina, Daniel; Ibáñez, Roberto; Belden, Lisa K

    2014-01-01

    The fungal disease chytridiomycosis, caused by Batrachochytrium dendrobatidis (Bd), is one of the main causes of amphibian population declines and extinctions all over the world. In the Neotropics, this fungal disease has caused catastrophic declines in the highlands as it has spread throughout Central America down to Panamá. In this study, we determined the prevalence and intensity of Bd infection in three species of frogs in one highland and four lowland tropical forests, including two lowland regions in eastern Panamá in which the pathogen had not been detected previously. Bd was present in all the sites sampled with a prevalence ranging from 15-34%, similar to other Neotropical lowland sites. The intensity of Bd infection on individual frogs was low, ranging from average values of 0.11-24 zoospore equivalents per site. Our work indicates that Bd is present in anuran communities in lowland Panamá, including the Darién province, and that the intensity of the infection may vary among species from different habitats and with different life histories. The population-level consequences of Bd infection in amphibian communities from the lowlands remain to be determined. Detailed studies of amphibian species from the lowlands will be essential to determine the reason why these species are persisting despite the presence of the pathogen.

  13. Hydrology and phosphorus transport simulation in a lowland polder by a coupled modeling system.

    PubMed

    Yan, Renhua; Huang, Jiacong; Li, Lingling; Gao, Junfeng

    2017-08-01

    Modeling the rain-runoff processes and phosphorus transport processes in lowland polders is critical in finding reasonable measures to alleviate the eutrophication problem of downstream rivers and lakes. This study develops a lowland Polder Hydrology and Phosphorus modeling System (PHPS) by coupling the WALRUS-paddy model and an improved phosphorus module of a Phosphorus Dynamic model for lowland Polder systems (PDP). It considers some important hydrological characteristics, such as groundwater-unsaturated zone coupling, groundwater-surface water feedback, human-controlled irrigation and discharge, and detailed physical and biochemical cycles of phosphorus in surface water. The application of the model in the Jianwei polder shows that the simulated phosphorus matches well with the measured values. The high precision of this model combined with its low input data requirement and efficient computation make it practical and easy to the water resources management of Chinese polders. Parameter sensitivity analysis demonstrates that Kuptake, cQ2, cW1, and cQ1 exert a significant effect on the modeled results, whereas KresuspensionMax, Ksettling, and Kmineralization have little effect on the modeled total phosphorus. Among the three types of uncertainties (i.e., parameter, initial condition, and forcing uncertainties), forcing uncertainty produces the strongest effect on the simulated phosphorus. Based on the analysis result of annual phosphorus balance when considering the high import from irrigation and fertilization, lowland polder is capable of retaining phosphorus and reducing phosphorus export to surrounding aquatic ecosystems because of their special hydrological regulation regime. Copyright © 2016 Elsevier Ltd. All rights reserved.

  14. Hydrogeologic framework of the Willamette Lowland aquifer system, Oregon and Washington

    USGS Publications Warehouse

    Woodward, D.G.; Gannett, Marshall W.; Vaccaro, J.J.

    1998-01-01

    This report summarizes the hydraulic characteristics of the materials that make up the Willamette Lowland aquifer system, ground-water movement in the aquifer system, estimates of ground-water recharge, ground-water quality characteristics, construction and use of cross-sectional numerical ground-water flow models, hydrologic controls on ground-water movement, water budgets and flow paths, and a description and application of a conceptual model.

  15. Successful treatment of acute systemic anaphylaxis in a western lowland</